Journal of the History of Biology 33: 247–289, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands.
247
T.H. Huxley’s Criticism of German Cell Theory: An Epigenetic and Physiological Interpretation of Cell Structure MARSHA L. RICHMOND Interdisciplinary Studies Program Wayne State University Detroit, MI 48202, U.S.A. E-mail:
[email protected]
Abstract. In 1853, the young Thomas Henry Huxley published a long review of German cell theory in which he roundly criticized the basic tenets of the Schleiden-Schwann model of the cell. Although historians of cytology have dismissed Huxley’s criticism as based on an erroneous interpretation of cell physiology, the review is better understood as a contribution to embryology. “The Cell-theory” presents Huxley’s “epigenetic” interpretation of histological organization emerging from changes in the protoplasm to replace the “preformationist” cell theory of Schleiden and Schwann (as modified by Albert von Kölliker), which posited the nucleus as the seat of organic vitality. Huxley’s views influenced a number of British biologists, who continued to oppose German cell theory well into the twentieth century. Yet Huxley was pivotal in introducing the new German program of “scientific zoology” to Britain in the early 1850s, championing its empiricist methodology as a means to enact broad disciplinary and institutional reforms in British natural history. Keywords: cell theory, morphology, Thomas Henry Huxley, physiology, Schleiden-Schwann cell theory, Romantic biology, scientific zoology, cytology, preformationism, natural history, epigenesis, Kernmonopol, histology, Albert von Kölliker, embryology
In October 1853, Thomas Henry Huxley (1825–1895) published a long “review” of German cell theory in which he roundly criticized the basic tenets of the Schleiden-Schwann cell theory. Appearing in one of Britain’s leading medical journals, Huxley’s attack on the cell doctrine had first been launched in an April 1853 lecture at the Royal Institution, an abstract of which appeared in a number of prominent organs of the scientific press.1 Such criticism, coming from a young and rising physiologist known for his familiarity with the latest German research, attracted considerable attention 1 T. H. Huxley, 1853b and 1853c. An abstract of his lecture appeared in the Edinburgh New Philosophical Journal, 53 (1853), 172–177 and in Quarterly Journal of Microscopical Science, 1 (1853), 307–311. In his review of recent literature, “Annals of Micrology,” British and Foreign Medico-Chirurgical Review, 13 (1854), p. 418, Robert D. Lyons judged it to include “much highly valuable original matter.” A reference to the work also appeared in the Medical Times & Gazette, 18 October 1856, p. 396.
248
MARSHA L. RICHMOND
in British scientific circles. In essence, it put forward a radically different way of viewing the “cell” than that of the German naturalists, one that emphasized the cell in relation to the histological development of the organism rather than viewing it as an independent unit and seat of organic vitality. Cell theory, as put forward in Theodor Schwann’s Mikroskopische Untersuchungen über die Übereinstimmung in der Struktur und im Wachstum der Thiere und Pflanzen (1839), had been well received in Britain, supported and extended by such prominent figures as Martin Barry, John Goodsir, Richard Owen, and William Benjamin Carpenter.2 Indeed, Carpenter, in discussing Huxley’s views in his 1856 presidential address to the Microscopical Society, acknowledged the significance of such forthright criticism of what had long been a well accepted premise of modern work in the life sciences. Since the publication of Schwann’s treatise, he noted, “almost every microscopic observer, down to a very recent period, who has devoted himself to this department of inquiry, has taken Schwann’s idea as his guide, and has considered it to be his main object to extend and complete it.”3 Huxley’s attack, then, represented a major break from orthodox opinion among medical researchers, microscopists, and naturalists that carried far-ranging implications for late nineteenth-century British biology. Despite the contemporary significance of Huxley’s attack on German cell theory, its historical import has not been widely discussed by historians of science. As Sherrie Lyons has pointed out, this in part stems from Huxley’s connection to Darwin, for critical aspects of Huxley’s pre-Origin research agenda have been neglected as a result of the prominent role he later played as proselytizer for Darwin’s evolution theory.4 Yet, in part the neglect to consider this aspect of his scientific work may also be due to the essay itself. Huxley’s review of cell theory is enigmatic for the historian, both in terms of its content and its message. The scientific details of Huxley’s criticism are difficult to comprehend for those not well versed in contemporary cytological literature and controversies. Moreover, Huxley’s own views seem paradoxical when judged by modern standards. Regarded as having been a “progressive” force in nineteenth century biology, his denigration of the cell as the ultimate structural unit of living organisms and the role of the nucleus in cell life are far removed from the theory of the cell upon which modern biology has been constructed. How, then, could Huxley have gotten it so terribly wrong? In response to this question, historians of cytology have primarily focused on the empirical errors that underlay Huxley’s position. John R. Baker, for example, referred to Huxley’s review as “an extraordinary episode” that 2 Jacyna, 1984. 3 Carpenter, 1856b, p. 23. 4 Lyons, 1995, pp. 465–66. See also Lyons, 1999.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
249
represented a retrograde step in the “course of progress.” Huxley, he asserted aimed “to discredit not only the view that protoplasm is the fundamental living substance, but also the cell theory as a whole.”5 Arthur Hughes was more generous in his assessment, drawing attention to Huxley’s philosophical opposition “to the conception of the individuality of the cell.” Yet he too believed that Huxley’s criticism was based on “a completely false view of the metabolic function of intercellular material.”6 More recently, Henry Harris and François Duchesneau have avoided the question by simply ignoring Huxley’s contribution to cytology altogether.7 Historians of biology, however, have been more circumspect in evaluating the development of cell theory, noting that the period between 1839 and 1861 was one of ongoing debates about central features of the cell, particularly the mechanism of cell generation and the understanding of what constitutes the “cell.” Not until the 1870s, as William Coleman reminded us, was the cell generally regarded as “a recognizable entity” and the nucleus the central organ in cell life. Rudolf Virchow’s emphasis on cell generation by division, encapsulated in his famous 1855 dictum “Omnis cellule a cellule,” and Max Schultze’s 1861 definition of the cell as a “mass of protoplasm containing a nucleus” inaugurated a new phase in cell theory. This new model of the cell, along with the complementary unicellular hypothesis of protozoa and protophyta, was incorporated into evolution theory by Ernst Haeckel in the mid-1860s.8 Yet a number of biologists continued to question orthodox opinion and express critical views about the validity of cell theory even after the 1890s, especially in Britain.9 It is in this context, then, that Huxley’s 1853 criticism finds greatest relief. Central to the mid-century debate over the importance of the cell in organic life were not merely differing interpretations of observational data but also contrasting conceptions of the organization of life. Shirley Roe has pointed out that in the eighteenth-century debate over preformation versus epigenesis, extrascientific issues motivated the scientific dispute. In this and other such controversies, she noted, “underlying, contextual elements” provide the “key motivational forces” and become a “forum for clashes between whole metaphysical systems.”10 This is especially true in the present case. Despite Huxley’s assertions about the empirical basis behind his rejection of Schwann’s cell theory, it was probably more his philosoph5 Baker, 1988, II, p. 95. 6 Hughes, 1959, pp. 132, 133. 7 Harris, 1999; Duchesneau, 1987. 8 Haeckel, 1866. See Rinard, 1981. 9 Coleman, 1971, p. 30 and 1965, pp. 126–127. For Britain, see especially Strick,
forthcoming. 10 Roe, 1981, pp. 148–149.
250
MARSHA L. RICHMOND
ical opposition to tenets underlying it that provoked his extremely critical response. Schwann’s cell theory, as Frederick Churchill has noted, “was above all else an embryological theory of the fine structure of the body.”11 Huxley also approached the microscopical structure of organic form in terms of its connection to the process of development. What distinguished his view from that of his German counterparts was his focus on the function of the cell in organic life rather than on the importance of its form. Huxley put forward a physiological interpretation of the cell in opposition to Schleiden’s and Schwann’s morphological conception. This realization provides an important guidepost for historians to use in evaluating “The Cell-Theory.” Rather than regarding Huxley’s piece, and indeed cell theory in general at mid-century, in terms more appropriate to the classical period of cytology after 1880, it is more instructive to view it in the context of the history of embryology. As Alice Baxter has shown, the debate over the chromosome theory of heredity circa 1900 represented a modern manifestation of the “preformationepigenesis controversy.”12 Indeed, the mid-century debate over the cell doctrine provoked by Huxley can likewise be viewed in embryological terms. When regarded as a tract presenting an “epigenetic” interpretation of early histological development to rival the “preformationist” cellular model of Schleiden and Schwann, Huxley’s “Cell-Theory” not only appears less anomalous but also assumes greater importance in the history of British biology. As the present paper attempts to show, Huxley viewed Schwann’s theory as a new form of preformationism that posed a threat to the principles of epigenetic development that guided his understanding of biological processes. The “Cell-Theory” can thus be seen as an attempt to present an alternative view at the microscopic level of the growth and development of an organism. Although Huxley’s concept of histological structure did not advance cytology, it did serve to focus biologists’ attention on epigenetic interpretations of development, and this tradition continued to resonate in British biology in future decades. Huxley’s essay also served to heighten an understanding of proper scientific methodology at a critical point in the history of British science. Huxley was a vocal member of a cohort of biologists, including Charles Darwin and Joseph Dalton Hooker, who were actively engaged in the reform movement of the 1850s. This group aimed to reform the study of natural history in Britain, in part through establishing a more empirically based and rigorous methodology in biology founded on a truly scientific morphology. Establishing a field with rigorous requirements for explanation was a 11 Churchill, 1991, p. 16. 12 Baxter, 1976, pp. 29–57.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
251
prerequisite for their aim of professionalizing biology in Britain. This entailed incorporating into natural history studies a focus on development and on the general laws governing organic form. Although drawing upon physiology, embryology, and comparative anatomy, the new biology was likewise to be demarcated from medicine. To enact their program, this group aimed to reform scientific institutions, including scientific societies, the natural history museum, and the universities.13 Huxley’s tract, therefore, must also be read as a manifesto for methodological reform. The present paper explores these important issues by focusing on the formulation and extension of Huxley’s views on the cell theory. The first section reviews Huxley’s initial acceptance of the cell doctrine as evidenced in his earliest papers (1845–1852), which reflected both his early medical training and the favorable reception accorded to the Schleiden-Schwann cell theory by the British biomedical community. Next, we examine Huxley’s role in introducing the new German morphological research program known as “wissenschaftliche Zoologie” to Britain in the late 1840s and early 1850s. Some of his earliest papers illustrate his adoption of scientific zoology, including its central focus on cells and the “unicellular hypothesis” of protozoa and protophyta. Then the evidence and arguments Huxley put forward in “The Cell-Theory” of 1853 in rejecting the Schleiden-Schwann cell theory are examined in detail, followed by suggestions about what may have prompted Huxley’s apparently abrupt volte-face. We conclude by evaluating the impact of Huxley’s views. We note that his emphasis on cell function rather structure, and on the cytoplasm rather than the nucleus, attracted a significant following among British biologists in subsequent decades. This was particularly true at Cambridge, where Huxley’s “new biology” became institutionalized in the research programs in physiology and morphology developed in the 1870s by Michael Foster and Francis Maitland Balfour. It was no coincidence, I suggest, that the most vocal opposition to August Weismann’s nucleus-based theory of heredity, and to German cell theory as late as the 1910s, came from Cambridge biologists. Furthermore, since cell theory formed a central component of scientific zoology, Huxley’s deviations meant that the British version differed in significant respects from its German counterpart. Yet in Britain as in Germany, the methodological reforms embodied in scientific zoology were used to promote broader reforms in the enterprise of natural history.
13 For a recent re-evaluation of “the professionalizing impetus” in mid-Victorian science that discusses the critical period of the early 1850s, see Barton, 1998.
252
MARSHA L. RICHMOND
Huxley’s Early Acceptance of Cell Theory From his student days on, Huxley placed great emphasis on microscopical acumen. While a medical student at Charing Cross Hospital between 1842 and 1845, at a time before microscopy courses were a part of the medical curriculum, Huxley supplemented Thomas Wharton Jones’s physiology lectures with his own independent study of microscopical technique.14 From his student notebooks we know that he examined a myriad of forms, including “the anatomy of insects, myriopods, molluscs and the life-cycles of flukes” as well as various Radiata, including protozoa, porifera, coelenterates, and echinoderms. Developing a mode of investigation that persisted throughout his career, Huxley explored first-hand the published descriptions of others, both in order to develop his own techniques as well as to corroborate their research findings.15 This method of inquiry led to his first publication in 1845, at the age of nineteen. Following up the observations of Jakob Henle, one of Germany’s leading microscopists, Huxley discovered a new layer of cells underneath the sheath of a human hair, which had not previously been detected.16 In addition to demonstrating his skill with the microscope, this paper also shows that Huxley was thoroughly familiar with Henle’s Allgemeine Anatomie (1841), which, as Arleen Tuchman notes, was one of the first works in which the microscope was used “to reinterpret organic form and development in light of the recent cell theory.”17 Huxley repeated Henle’s instructions for dissecting the hair sheath, treating the hair with acetic acid to harden the external covering, then splitting it “longitudinally with needles or a fine knife” and removing it, thereby revealing in the “the fenestrated membrane” “a single layer of very pale epithelium-like nucleated cells” that continues to be known as “Huxley’s layer.”18 Certainly, Huxley in 1845 was already an adept microscopist who readily adopted the newest techniques, including the use of various acids and chemicals as hardening or preserving agents and different stains, despite Wharton Jones’s admonition that they unnatur-
14 L. Huxley (ed.), 1913, 1: 30; Desmond, 1997, p. 26. Huxley’s self-instruction in microscopy was necessary since few such courses were offered in the mid-1840s, either in Germany or the United Kingdom. For Germany, see Tuchman, 1993; for Britain, see Bracegirdle, 1978, p. 311. 15 Hollowday, 1995, p. 441; Desmond, 1995, pp. 26, 652, n. 27. 16 T. H. Huxley, 1845, p. 1340. 17 Tuchman, 1993, p. 63. 18 Hollowday, 1995, p. 440.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
253
Figure 1.
ally altered living tissue.19 Moreover, like mainstream British anatomists and physiologists, Huxley in the 1840s accepted the nucleated cell as the basic structural feature of living tissues (see Figure 1).
Transcendental Morphology and the Reception of the Schleiden-Schwann Theory in Britain As L. S. Jacyna has shown, the Schleiden-Schwann cell theory, first sketched out in 1838 and systematized in Schwann’s 1839 book, “was rapidly and easily accepted in Britain.” This Jacyna believes was a consequence of physiologists having previously adopted the German “romantic programme for biology.” “British workers took up the concept of the cell as a means of characterizing more adequately the point of unity between the highest and lowest forms of life. They hoped thereby to elucidate the fundamental vital 19 See anonymous, 1891. See also Hollowday, 1995. On the generational differences
between using chemical reagents among microscopists in the 1830s and their younger cohorts of the 1840s, see Schickore, 1999.
254
MARSHA L. RICHMOND
processes.”20 Especially centered in Edinburgh, the Romantic program was extended in the late 1830s and early 1840s by the writings of Martin Barry and the lectures of William Sharpey, both of whom had studied in Germany.21 In two influential papers of 1837, Barry directed the attention of British naturalists to the “vast” importance of Karl Ernst von Baer’s laws of embryonic development.22 Stimulated by Barry’s articles, William Benjamin Carpenter introduced British researchers to von Baer’s developmentalist research program through his influential textbook Principles of General and Comparative Physiology, first published in 1839 and refined through four editions, the last published in 1854. This book “did more than any other work to make von Baer’s ideas known to the English-speaking world.”23 Both Barry and Carpenter readily accepted cell theory, especially the concept of the cell as embodying the unity between the animal and vegetable kingdoms. As Carpenter noted, “[i]t is interesting to remark that the simple cell, which is the type of the lowest plant as well as of the lowest animal, is also the type of the earliest embryonic condition in both kingdoms; and there is no more perceptible difference between the germ of a plant and an animal, than there is between those of the different classes of either kingdom.”24 But it was Barry who particularly adopted Schleiden and Schwann’s view of the nucleus as the most significant morphological and physiological feature of cells.25 Indeed, having worked with Schwann in the 1830s in Johannes Müller’s Berlin laboratory, Barry developed novel ideas about the role of the nucleus in cell division and growth after Schwann had abandoned further work on cell theory.26 With his teacher Wharton Jones, himself a product of the Edinburgh school of medicine, also focused on cells, it is not surprising that Huxley, in his earliest papers, accepted the nucleated cell as the structural unit of tissues and embraced the theoretical assumptions included in cell theory.27 20 Jacyna, 1984, p. 22. 21 Haines, 1957, pp. 37–38. 22 Barry, 1837a, 1837b. See also Barry, 1838, p. 302. 23 Ospovat, 1976. 24 Carpenter, 1837, p. 113. See also Carpenter’s enthusiastic review of Schwann’s book (Carpenter, 1840). 25 See Barry, 1847; Schwann, 1839, pp. 18, 19. 26 Barry pointed out that his views of “cellular development” differed widely from those of Schleiden and Schwann. Rather than viewing the nucleus as “remaining inert in the cellwall, or being absorbed as useless,” he described the nucleus as “a most active agent, and endowed with properties of the first importance,” including “an attractive force” that operated in fecundation and metabolism (Barry, 1847, pp. 202, 210–218). He also suggested that particles of the “hyaline” nucleus, “which are the true cell-germs, may assume an independent life in the form of Infusoria; and thus go far to explain the so-called spontaneous generation” (p. 221). 27 L. Huxley (ed.), 1913, 1: 37.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
255
Huxley, Developmental Morphology, and the Program of wissenschaftliche Zoologie As Mary P. Winsor has so beautifully described, Huxley established his reputation as a young and rising British physiologist on the basis of his notable successes in applying the morphological type concept in classifying hydrozoa and other members of the Radiata.28 Indeed, Huxley claimed that he “learned the meaning of Morphology and the value of development as the criterion of morphological views – first from the study of the Hydrozoa . . . and secondly, from the writings of Von Bär.”29 Grounded in a conception of the unity of organization in nature, the type concept was a key feature of the morphological tradition that built on von Baer’s laws of embryonic development. In the 1830s and 1840s, as it well known, von Baer’s view of the common plan of diverging embyological development was incorporated into the research program that Edward Stuart Russell called “functional” morphology and Timothy Lenoir labeled “developmental” morphology, reserving “functional morphology” to denote a different variant of the overall “teleomechanistic” program in German morphology.30 In Britain, the earlier tradition of “transcendental” or Romantic morphology, which posited common “archetypes” underlying the different plans of animal organization, was represented not only in the work done by Barry and Carpenter but also in that conducted by Richard Owen. Yet, beginning in the late 1840s. Romantic morphology began to be complemented by the emerging variant of “scientific zoology,” and in this transmission Huxley figured prominently.31 28 Winsor, 1976. See also J. Huxley, 1936, pp. 36–58. 29 Letter to Rudolf Leuckart, January 1859, in L. Huxley (ed.), 1913, 1: 234. 30 Russell, 1917; Lenoir, 1989. 31 This is not to imply, however, any simplistic dichotomy between these two variants. As Adrian Desmond has shown (Desmond, 1989), the British morphological tradition in the 1840s exhibited complex variation in its social, institutional, and ideological allegiances and accommodations. In addition, Phillip Sloan has pointed out that “we cannot adequately conceive the philosophical relationship within German biology in these early decades of the nineteenth century in terms of competing research programs,” for naturalists, following different aspects of Kant’s program, often vacillated between transcendentalism or rigorous empiricism depending on the kind of inquiry they were pursuing. See Sloan, 1992, pp. 31– 33. On Owen’s transcendentalism, see ibid., p. 62, n. 178; p. 201, n. 81; E. Richards, 1987. Lynn Nyhart has pointed out that Russell “completely ignored the existence of a functionalist tradition in Germany, thereby framing the problematic of German morphology in terms of the continuity or discontinuity between idealistic morphology, Haeckelian evolutionary morphology, and causal-experimental morphology” (Nyhart, 1995a, p. 31). The same is true in Britain, where the introduction of a new “scientific” morphological methodology alongside transcendental morphology prior to the publication of Darwin’s Origin of Species has not been generally recognized. See, for example, di Gregorio, 1984, pp. 38–39.
256
MARSHA L. RICHMOND
In many of the papers on invertebrate morphology published soon after his return to England, Huxley displayed his familiarity with the literature of the new German program of “scientific” botany and zoology. Having accepted Schleiden’s call for a more empirically based methodology in biology in response to Naturphilosophie, followers of scientific zoology in the 1840s sought to reform natural history – to make it “scientific” – by focusing on development as the means of discovering the laws underlying plant and animal form. The tenets of this program were first enunciated in the short-lived Zeitschrift für wissenschaftliche Botanik (1844–1845), edited by Schleiden and his student Carl Nägeli, and carried on in the Zeitschrift für wissenschaftliche Zoologie, founded in 1848 by Karl Theodor Ernst von Siebold and Albert Kölliker. With the aim of discovering “the lawful organization of the organic realms,” scientific zoologists employed the approaches and tools of comparative anatomy, histology, physiology, and developmental history in the study of natural history, since, as Siebold stated, “mere systematics – the establishment of new genera and species – does not alone constitute the science of zoology.”32 Scientific botanists and zoologists, as Lynn Nyhart has noted, basically sought to “unite classification with the studies of animal function and organization in the synthetic framework provided by functional morphology.”33 Despite not being represented in Russell’s or Lenoir’s categorization of German morphology, scientific zoology was an important variant of developmental morphology in the late 1840s and 1850s.34 Several significant features set it apart form earlier morphological traditions: followers adhered to a strictly empirical methodology – following the guidelines laid out in Schleiden’s famous “Methodological Introduction” to the Grundzüge der wissenschaftlichen Botanik (1842–1843) – in which the microscope became a critical tool.35 Moreover, cell theory became a central component of scientific zoology, both providing a shared consensus for interpreting observation and serving as the physical embodiment of the long-held principle, carried over from Naturphilosophie, about the underlying unity in nature. For scientific zoologists, in contrast to Naturphilosophen, the cell provided the means by which the unity of organic structure could be investigated scientifically. 32 The prospectus for the new journal, circulated in February 1848, is reprinted in Ehlers,
1885, p. xiii. For Siebold, see Körner, 1967, p. 307. 33 Nyhart, 1991. See also Nyhart, 1995a, p. 98. Nyhart also believes that Lenoir’s categorization of “functional morphology” is too restrictive to fully characterize the program of scientific zoology (ibid., p. 31). 34 Nyhart, 1995a, p. 31. 35 Buchdahl, 1973.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
257
A further central feature of scientific zoology was the generally accepted identification of the lowest plants and animals as “cells” – the so-called “unicellular hypothesis” of protozoa and protophyta – developed by Siebold in 1845 and elaborated by him and others in early issues of Zeitschrift für wissenschaftliche Zoologie.36 Such simple organisms, as Nägeli noted in 1845, offered a natural entrée into understanding basic cellular organization and function, for “the animal kingdom begins with animals formed from a few simple cells.”37 Viewed as “archetypical” exemplars of cells in nature, unicellular plants and animals were regarded as particularly suitable objects for investigating fundamental cell structure and function. It is not surprising, then, that such a dynamic reform movement in natural history, founded on exact empirical studies and with the aim of uncovering the laws governing the organic world comparable to those of chemistry and physics, was not confined to Germany, and that it also found a significant following among a small coterie of British naturalists. After returning to England following the voyage of the Rattlesnake (1846–1850), Huxley was actively engaged in elaborating a number of the invertebrate studies undertaken at sea. In this endeavor he found support from a number of naturalists, among whom Edward Forbes figured prominently. Although in many respect Forbes continued to exhibit elements of transcendental morphology learned while a student at Edinburgh, he was also highly appreciative of the empirical focus and practical results coming out of scientific zoology. Forbes approached his studies in a similar vein to his German counterparts, claiming, for example, that a systematic understanding of zoophytes would only come from “naturalists expert in physiological and anatomical investigations, skilled in the use of the microscope, and not too trustful in its revelations.”38 For a young naturalist such as Huxley, more concerned, as he stated in his 1849 paper on the Medusae, with providing “broad and general views of the whole class” rather than “stating matters of detail concerning particular genera and species,” it is easy to understand why he judged Forbes to have “more claims to the title of a Philosophic Naturalist than any man I know of in England.”39 It is also understandable why Huxley would have been interested in the new works of scientific zoology, to which 36 Siebold [1845–1848], p. 15. The first ten volumes of the Zeitschrift für wissenschaftliche
Zoologie (1848–1860) include 24 articles on protozoa and protophyta by Kölliker and Siebold, as well as by Alexander Ecker, Ferdinand Cohn, Franz Leydig, Franz Stein, Carl Vogt, Anton de Bary, and Leopold Auerbach. Kölliker particularly noted the great importance of singlecelled animals for zoology and natural history (Kölliker, 1845, p. 97, n. 1). See also Churchill, 1989, p. 195. 37 Nägeli, 1844, p. 24. See also Jahn et al., 1982, pp. 331–332. 38 Forbes, 1848, p. 2. See also Rehbock, 1983. 39 See L. Huxley (ed.), 1913, 1: 136–137.
258
MARSHA L. RICHMOND
Forbes and others introduced him. Both George Busk and Edwin Lankester, for example, shared Huxley’s “biological interest and social conscience,” as well as his appreciation for the new work coming out of Germany.40
Huxley, Cell Theory, and the Unicellular Hypothesis of Protozoa, 1851 Huxley’s familiarity with the recent literature and theoretical underpinnings of scientific zoology, including cell theory, can be seen in an 1851 paper, in which he described a “new Zoophyte” discovered during his voyage that he christened Thalassicolla (“sea jelly”).41 Thalassicolla, commonly found floating on the sea’s surface, was described by Huxley as “transparent, colourless, gelatinous masses of very various form” having few structural features and exhibiting no evidence of contractility or locomotion. He did, however, discern two different forms. T. punctata was “a mass of cells united by jelly,” while T. nucleata appeared to be “a much enlarged condition of single cells of the Th. punctata.” Convinced that the two forms were not larval stages of a more “highly-organized animal,” Huxley next considered their zoological affinity. In this discussion, he demonstrated both a thorough knowledge of the recent literature in scientific zoology as well as the recent controversy concerning the unicellular hypothesis. By characterizing the protozoa as “[a]nimals in which the different organ systems are not distinctly separated, and whose irregular form and simple organization can be reducible to the type of a cell,” Siebold and other scientific zoologists directly challenged Christian Gottfried Ehrenberg, who since the 1830s had expounded the view of protozoa as miniature organisms, replete with complete organ systems.42 Although Owen had expressed his acceptance of Ehrenberg’s views, Huxley came down on the side of the scientific zoologists, identifying Thalassiccola as a unicellular animal. What animals are there then which consist either of simple cells or of cells aggregated together, which hold the same rank among animals that the Diatomaceae and Desmidiae, the Protococci and Palmellae hold among plants? Ten years ago the general reply of zoologists would have been – none. The researches of the celebrated Berlin microscopist, Prof. Ehrenberg (wonderful monuments of intense and unremitting labour, but at least as 40 Forbes, for example, loaned him Frey and Leuckart’s Beiträge zur Kenntniss wirbelloser
Thiere. See T. H. Huxley, 185lb, p. 374. On Huxley’s shared interests with Busk and Lankester, all of whom translated German scientific works into English, see Desmond, 1995, p. 159. 41 T. H. Huxley, 1851c. 42 See Churchill, 1989.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
259
wonderful illustrations of what zoological and physiological reasoning should not be), led to the belief that the minutest monads had an organization as complicated as that of a worm or a snail. In spite, however, of the great weight of Prof. Ehrenberg’s authority, dissentient whispers very early made themselves heard, from Dujardin, Focke, Meyen, Rymer Jones, and Siebold. To these Kölliker, Stein and others – in fact, I think I may say all the later observers – have added themselves, until it really becomes a matter of duty on the part of those interested in the progress of zoology to pronounce decidedly against the statements contained in the “Infusionsthierchen,” so far as regards anatomical or physiological facts.43 Although acknowledging that “the majority of English readers” would consider these remarks “to be unwarrantably severe,” Huxley simply trusted what he observed under the microscope, and directed others to do the same and compare Ehrenberg’s descriptions “with facts.” In so doing, however, he was also challenging the authority of Owen and, by implication, others who were not as empirically grounded as scientific zoologists. Despite an admittedly incomplete understanding of the anatomical structure of Thalassiccola, Huxley next ventured a view of “their relations in the scale of being.” It was in this context that he demonstrated his acceptance of the unicellular hypothesis. Following Siebold, he removed many of Ehrenberg’s “Polygastria” to the vegetable kingdom. He then described the Protozoa as “animals which are either simple nucleated cells, or such cells as have undergone a certain amount of change, not sufficient however to destroy their real homology with nucleated cells.” Noting that nuclei had been found in most known protozoan genera, Huxley thus concluded that Thalassicolla could also be considered a “unicellular” animal – that is, an animal “which either consist[s] of a single cell, or of definite aggregations of such cells, none of which possesses powers or functions different from the rest.”44 Protozoa, the lowest group of animals bordering the plant kingdom, he regarded as divisible into four different “types”: the Polygastria, Gregarinidae, Infusoria, and Foraminifera. He placed Thalassicolla within the Polygastria. Compared with the next highest group, the sponges, all four types could be regarded as “ ‘unicellular’ animals,” two of which consisted of isolated cells and two of aggregated cells. In this view, T. punctata was given added significance by Huxley as an organism representing “the connecting link between the Sponges and the Foraminifera” by virtue of its texture, 43 T. H. Huxley, 1851c, p. 88. See also Desmond, 1995, p. 177 and n. 10. 44 T. H. Huxley, 1851c, pp. 89–91.
260
MARSHA L. RICHMOND
spicules, and perforated shell.45 Apart from purely morphological considerations, it appeared from recent findings that unicellular animals underwent a process of reproducing through “endogenous” division (that is, by fission or gemmation), “preceded by a process analogous to the conjugation of the lower plants.” Accordingly, Huxley speculated that T. nucleata might simply be the reproductive stage of T. punctata, similar to the independent reproductive cells that had recently been observed in Gregarinidae and in certain freshwater sponges. Although admitting the “hypothetical grounds on which some of these conclusions rest,” he offered them “to show the tendency of the evidence now extant as clearly and broadly as possible.”46 Huxley concluded this piece by discussing the connection between the Schleiden-Schwann cell theory and the form of the simplest animals and plants. Here again he affirmed his acceptance of the nucleated cell as the “ultimate histological element of animal tissues.” “This is not the place,” he stated, “to discuss the important question, whether the great law developed by Schwann does or does not hold good among the whole of the lower animals. I believe that there is evidence to show that it does; that everywhere careful analysis will demonstrate the nucleated cell to be the ultimate histological element of the animal tissues; and that the ‘sarcode’ of Dujardin, and the ‘formless contractile substance’ of Ecker, are either cells or cell-contents, or the results of the metamorphosis of cells.”47 As this paper demonstrates, in 1851 Huxley accepted both the principle tenets of German cell theory and endorsed the unicellular hypothesis of protozoa. As we have seen, such a position was not novel among British naturalists. Many other leading figures in British biology, including Barry, Owen, and Carpenter, also accepted cell theory and (with the exception of Owen) the identification of protozoa and protophyta with cells.48 It also shows that Huxley was thoroughly familiar with the latest research on unicel45 On Huxley’s use of William Sharp MacLeay’s “circular system” to classify invertebrates, see Winsor, 1976, chap. 4 and p. 97; Desmond, 1995, pp. 89–90. In this approach, Huxley himself exhibits remnants of transcendental morphology. 46 T. H. Huxley, 1851c, pp. 91–95. 47 T. H. Huxley, 1851c, p. 90. 48 In his review of Schwann’s Mikroskopische Untersuchungen, Carpenter wrote: “It is interesting to remark that the simple cell, which is the type of the lowest plant as well as of the lowest animal, is also the type of the earliest embryonic condition in both kingdoms; and there is no more perceptible difference between the germ of a plant and an animal, than there is between those of the different classes of either kingdom” (Carpenter, 1840, pp. 495–528). See also Carpenter, 1856a, pp. 28–29. Although recognizing in infusoria the “striking analogies to the cells out of which the higher animals can all their tissues are developed,” Owen supported Ehrenberg’s interpretation, stating that “no mere organic cell, destined for ulterior changes in living organisation, has a mouth armed with teeth, or provided with long tentacula,” which “raises the Polygastric Infusoria much above the mere organic cell.” See Owen, 1843, p. 366.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
261
lular organisms coming out of the program of scientific zoology, which he thus introduced to British comparative anatomists and physiologists. In this and other early papers, we note his focus, shared with other scientific zoologists, on an empirically based methodology grounded in developmental morphology. Yet we also see his willingness to engage in speculation, so long as it is based on “facts.” Two years later, however, Huxley completely reversed himself, repudiating every essential tenet of German cell theory, including the unicellular hypothesis. This seeming paradox, especially in light of his continuing advocacy of scientific zoology, is made less anomalous when regarded in a broader context, as it signifies both his more mature consideration of morphological methodology, and his new vision of how a strictly empirical methodology, shorn of questionable “transcendental” principles, could form the basis for reform in British natural history and the professionalization of biology.
Huxley and von Baer Huxley’s early understanding of the program of developmental morphology, as evidenced by his papers published prior to 1853, was not based on a first-hand acquaintance with the writings of von Baer. Only after his return from his voyage did he first read von Baer’s celebrated “Fifth Scholium” – the section of Ueber die Entwickelungsgeschichte der Thiere that discusses the doctrine of embryonic divergence and recapitulation.49 The methodology Huxley employed in studying the anatomy of various marine invertebrates while on board the Rattlesnake was gleaned from other sources, including Wharton Jones’s lectures and his own extensive reading of pivotal German works, especially Johannes Müller’s Handbuch der Physiologie des Menschen (1833–1834) and Henle’s Allgemeine Anatomie (1841).50 By the time of his return to England in October 1850, Huxley was well versed in the practical application of developmental morphology, but he only became conversant with the philosophical underpinnings after reading von Baer’s text, to which he may have been directed by Carpenter’s Principles of Physiology. Shortly after returning to London, Huxley made Carpenter’s acquaintance and agreed to help him revise the new Third edition of his work that he was preparing, and that was published in 1851. In it Carpenter 49 In a letter to Darwin, 23 November 1859, Huxley stated: “Since I read Von Bär’s Essays nine years ago no work on Natural History Science I have met with has made so great an impression upon me” (Darwin, 1985–, 7: 390). 50 See, for example, L. Huxley (ed.), 1913, 1: 16–18; and Desmond, 1995, pp. 25–26, and 652, n. 27, in which the works Huxley read as a student, as recorded in his notebook (c. 1845), are listed. On Müller’s application of von Baer’s principles, see Lenoir, 1985, pp. 95–111.
262
MARSHA L. RICHMOND
first adumbrated, drawing on von Baer, the parallel between embryological development and the fossil record.51 In any event, two years later, in 1853, Huxley published a translation of portions of von Baer’s treatise with the expressed aim of familiarizing British naturalists with von Baer’s notion of “development as the sole basis of zoological classification.”52 In the wake of a resurgence of interest in transcendental morphology in Britain, promoted by the recent appearance of an English edition of Lorenz Oken’s Elements of Physio-Philosophy (1847), Huxley’s translation of von Baer’s writings proved pivotal.53 It prompted Carpenter to revise his account of von Baer’s law of divergence, previously drawn from Barry’s 1837 articles, in the fourth edition of Principles (1854), which in turn influenced not only Darwin but also Herbert Spencer and other young biologists.54 Indeed, it was Huxley’s translation – the “second wave” in the introduction of von Baer to England – that Darwin appears to have cited in Origin of Species when he described the importance of von Baer’s comparative embryology for understanding the process of evolution.55 Huxley’s first published reference to von Baer’s work came in his 1853 paper, “On the Morphology of the Cephalous Mollusca,” in which he described in detail his understanding of the archetype concept.56 Certainly, 51 Carpenter was responding to Owen’s claim that he first developed the notion of general to
special development. See Ospovat, 1976, p. 22, n. 75. Huxley later recalled meeting Carpenter, stating: “I was a very young man, almost friendless in the scientific world, when I returned to England in the end of 1850. I made Dr. Carpenter’s acquaintance early in 1851, and it so happened that I was able to give him some odds and ends of information, which he found useful in bringing out the third edition of the ‘Principles of Comparative Physiology.’ ” See Carpenter, 1888, p. 139. According to W. T. Thiselton-Dyer (Thiselton-Dyer, 1925, p. 710), Huxley also helped revise the fourth edition of Principles (1854). 52 T. H. Huxley (trans.), 1853, p. 176. 53 According to Robert Knox, a staunch transcendentalist writing in 1856, since Oken’s work had been translated, “the doctrines of this worthy and simple-minded enthusiast have been all the rage in England, taken up con furore on this side of the channel.” See Rehbock, 1983, p. 39. 54 Darwin owned and extensively annotated the 4th edition of Carpenter’s Principles. See Darwin, 1985–, 4: 492; di Gregorio and Gill, 1990. On Spencer, see Gould, 1977, p. 112. See also Thiselton-Dyer, 1925, p. 710; Foster, 1895, p. 319. 55 In the first volume of his monograph on Cirripedia, published in 1851, Darwin drew on Henri Milne-Edwards’s formulation of the embryological criterion for indicating homological relationships. In the second, published in 1854, however, he cited von Baer’s views on increasing “morphological differentiation” to discern “higher and lower” forms among the cirripedes. See [Richmond], 1988, pp. 391–392. See also R. Richards, 1991, pp. 106–108. 56 T. H. Huxley, 1853a; Scientific Memoirs, 1898, 176; the reference to von Baer is on page 182. Sherrie Lyons’s statement that Huxley used “von Baer in virtually all his memoirs on the invertebrates” should thus be modified to read “after 1853” (Lyons, 1995, p. 472, n. 47). See also Desmond, 1995, pp. 174–176.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
263
from this time forward he began to distinguish his own conception of the archetype from the transcendental conception held by Owen, whose differing methodological approach to biology contributed to their increasing animosity.57 It is clear, then, that von Baer’s work made a great impression on Huxley, sharpening his understanding of the theoretical principles of developmental morphology as well as his focus on methodological concerns. As Huxley told the German zoologist Rudolf Leuckart in 1859, since returning from his voyage he had made it his aim to instill a more empirically based and morphologically oriented research methodology into zoological research. Particular branches of zoology have been cultivated in this country with great success, as you are well aware, but, ten years ago I do not believe that there were half a dozen of my countrymen who had the slightest comprehension of morphology, and of what you and I should call “Wissenschaftliche Zoologie.” Those who thought about the matter at all took Owen’s osteological extravaganzas for the ne plus ultra of morphological speculation. I have done by best, both by precept and practice, to inaugurate better methods and a better spirit than had long prevailed. Others have taken the same views, and I confidently hope that a new epoch for zoology is dawning among us.58 As this passage makes evident, Huxley associated “scientific zoology” not only with the new morphology, distinct from the transcendental variant represented by Owen and his followers, but also with methodological reform. Yet, he soon same to realize that not all the views associated with German scientific zoology lived up to his high expectations concerning a morphology devoid of unjustified “speculation.” The turning point appears to have come when he and his friend George Busk undertook a translation in 1852 of Albert Kölliker’s new textbook on human histology, Handbuch der Gewebelehre. In it Huxley encountered in Kölliker’s writings the latest version of the Schleiden-Schwann cell theory, one that he found highly objectionable on a number of fronts. When viewed against this backdrop, then, Huxley’s 1853 review of cell theory takes on new meaning: it represents both a criticism of German cell theory and a manifesto for a British version of scientific 57 On Owen’s archetype concept, see Rupke, 1993; on the influence of Oken’s transcendental morphology on Owen in the early 1850s, see Strick, forthcoming, chap. 2; and Desmond, 1989, chap. 6. For the increasingly acrimonious conflict between Huxley and Owen after 1854, see Desmond, 1982, chap. 1, and Desmond, 1995, chaps. 10 and 11. See also di Gregorio, 1984. 58 L. Huxley (ed.), 1913, 1: 234.
264
MARSHA L. RICHMOND
zoology, one devoid of overly theoretical speculation about the seat of organic vitality and nature of organization. It was also one in which a preformationist interpretation of cells was replaced by an epigenetic conception.
Huxley on Cell Theory Huxley’s “The Cell-Theory” of 1853 was a “critical and analytical review,” not of recent books but of the topic itself. Published in one of the leading organs of British medical science, the British and Foreign MedicoChirurgical Review, Huxley’s views were assured a wide readership.59 Indeed, this consideration appears to have led him to alter his original plan of publishing the piece in a “General Appendix” at the end of Kölliker’s Manual of Human Histology.60 In the event, the long criticism of cell theory was published independently before the second volume of the Manual appeared. Kölliker’s Views of the Cell The first histological text to incorporate the tenets of cell theory, Kölliker’s Manual begins with a fifty-page consideration of cell theory. Kölliker, whose writings and position as co-editor of the Zeitschrift für wissenschaftliche Zoologie had made him into one of the leading authorities in scientific zoology, fully supported cell theory and the unicellular conception of protophyta and protozoa. Nonetheless, incorporating the results from the last dozen years of research, Kölliker’s model of the cell differed to some extent from the one proposed by Schwann. He recognized, for example, that a third mode of cell development, fissiparous cell formation (simple division), could be discovered in some unicellular forms, in addition to the free-cell formation (“exogenous” formation in the cytoblastema) and the endogenous cell formation (daughter or secondary cells forming within the mother cell) described by Schwann. Yet along with Schwann, Kölliker continued to recognize endogenous development as the most prevalent mode of cell reproduction.61 In addition to discussing new empirical findings regarding cell structure and development, Kölliker also considered key theoretical questions. One of the central features of the Schleiden-Schwann cell theory was the attempt to avoid any assumption of a vital force guiding the processes of the living cell by comparing new cell formation to the physical process of 59 T. H. Huxley, 1853c. (Hereafter, pages in both the original and reprint edition will be cited.) 60 Kölliker, 1853–1854, pp. vii–viii. 61 Duchesneau, 1987, pp. 233–253.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
265
crystallization.62 Kölliker, however, rejected this analogy, stating that simple molecular attraction could account for organic phenomena as it did for inorganic reactions. He similarly rejected Schwann’s attribution of a “special metabolic force” to explain cell growth and development, again holding that such processes resulted from “known molecular forces.” Yet he went further than Schwann in emphasizing the role of the nucleus as the most important element of cellular structure. Schwann, following Schleiden, believed “the most important and abundant proof as to the existence of a cell is the presence or absence of the nucleus,” and further noted its central importance as the locus for new cell generation.63 Kölliker, although likewise viewing the nuclei as defining the cell and as “proper centres of development (bildungspunkte) of the young cells,” also endowed them with the further role of directing metabolic function by attracting nutrient molecules from the cytoblastema.64 It was this ascription of special powers to the nucleus – at one point described as resulting from a special “nuclear force” – that brought forth the ire of Kölliker’s British translators and fellow “scientific zoologists.” Such assumptions were not directly derived from observation, and they also carried profound philosophical implications for conceptualizing the organization of life. It is clear that Huxley and Busk strongly objected to many of Kölliker’s theoretical assumptions. “We must altogether demur,” they wrote in a note appended to Kölliker’s discussion of egg cell cleavage, “to the notion that the ‘nuclei’ of the dividing yelk exercise any attraction upon the yelk substance,” citing the observations of a number of investigators that “appear to furnish demonstrative evidence that no such attraction exists.”65 They also included textual annotations, extending over three pages, to Kölliker’s description of “the nature and mode of development of connective tissue” from cells, directing the reader to the intended “General Appendix” for further discussion. In the end, their contrasting views about the nature of cells
62 Schwann, 1847. This work also included a translation of Matthias Jacob Schleiden’s “Beiträge zur Phytogenesis” (1838). Schleiden emphasized that his theory of cell genesis avoided the necessity for “the aid of a deus ex machina (the generatio spontanea)” (p. 249), while Schwann claimed his theory provided a “physical” rather than “teleological” explanation “of the fundamental powers of organized bodies” (p. 188). On the importance for functional morphologists of eliminating the invocation of vital forces to explain the phenomena of life, see Lenoir, 1989, pp. 188–189. 63 Schwann, 1847, p. 18. See Duchesneau, 1994. 64 Kölliker, 1853–1854, pp. 31, 34, 42; Duchesneau, 1994, pp. 112–114. Kölliker’s views regarding the nucleus were similar to those previously expressed by Barry in 1847. For the importance of Kölliker’s text for German morphology, see Nyhart, 1995a, pp. 85–90. 65 Kölliker, 1853–1854, p. 25, n. 2.
266
MARSHA L. RICHMOND
and histological differentiation were more fully discussed in Huxley’s “The Cell-Theory.” “The Cell-Theory” Huxley’s review of cell theory lists twelve works to be considered, only seven of which were recent. These included the treatise De Partibus Similaribus by the sixteenth-century author G. Fallopius; four works by the eighteenthcentury embryologist Caspar Friedrich Wolff, von Baer’s Entwickelungsgeschichte der Thiere; and contemporary works by Schleiden, Schwann, Karl B. Reichert, Hugo von Mohl, Kölliker, and (the sole British work) Carpenter’s “On the Relations of the Vital and Physical Forces” (1851). This list initially seems to be an odd assortment. Huxley cited the older texts to support his understanding of the organization of life; among the modern works, only those of Reichert and von Mohl fall into that category; all the others are ones he criticizes. Huxley began his essay by surveying the definitions given by older biologists to characterize living bodies, focusing on the continual process of change and development organisms undergo. Quoting a passage from Fallopius’s 1562 work, Huxley remarked that, after substituting “modern terms of equivalent meaning,” it “would serve very well as a concise expression of the ‘cell-theory,’ such as may be found in many a hand-book of the day. So far, and no further have three centuries brought us!” “In fact, it must be confessed,” he continued, “that these old writers were fully possessed (more so, in truth, than many of their successors,) with the two fundamental notions of structural and physiological biology; the first, that living beings may be resolved anatomically, into a comparatively small number of simple structural elements; the second, that these elementary parts possess vital properties, which depend for their manifestation only upon the existence of certain general conditions . . . and are independent of all direct influence from other parts.”66 Lest he be considered too irreverent, however, Huxley did pay homage to the importance of Schleiden’s and Schwann’s cell theory. “Whatever cavillers may say, it is certain that histology before 1838 and histology since then, are two different sciences – in scope, in purpose, and in dignity.” Yet, the importance of Schwann’s Mikroskopische Untersuchungen was not that it greatly advanced the knowledge of histological structure, but rather in the stress it placed on histological development. It was, he noted, an excellent illustration of William Whewell’s notion of the value of theories as serving to “colligate” the facts. This having been said, however, Huxley proceeded 66 T. H. Huxley, 1853c, p. 224; 1898–1901, 1: 246.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
267
to analyze these “facts,” aiming to show that they were erroneous and hence supporting his contention that “the cell-theory of Schleiden and Schwann” was not only “based upon erroneous conceptions of structure,” but it also led “to errors in physiology.”67 Schleiden’s views of plant cells were the immediate target of Huxley’s criticism. Huxley listed three of Schwann’s assumptions based on Schleiden’s botanical data that Huxley believed were erroneous: 1. The prevalent notion of the anatomical independence of the vegetable cell, considered as a separate entity. 2. The prevalent conception of the structure of the vegetable cell. 3. The doctrine of the mode of development.68 Taking each point in series, Huxley attempted to show that it could be refuted on the basis of either new empirical evidence or questionable theoretical principles. As for the anatomical independence of cells, Huxley noted that Schleiden had come to this conclusion after treating vegetable tissues with “certain chemical or mechanical means” that caused them to “be broken up into vesicles corresponding with the cavities which previously existed in it.” Hugo von Mohl’s recent studies, however, indicated that this view rested “on imperfect chemical investigation,” and that in fact “there exists no real line of demarcation between one cell and another” but rather evidence that in tissues treated “mechanically or chemically” “the continuous cellulose substance has been torn or in some way destroyed.” Huxley corroborated von Mohl’s conclusions through his own studies. In young plant tissues treated with sulphuric acid and iodine, the “partitions” originally observed subsequently disappeared. “The cellulose substance forms a partition between cavity and cavity, which becomes evenly blue throughout . . . and . . . even under the highest powers, exhibits no symptom of any optical difference.”69 This point is of interest. First, Huxley used a chemical test developed by Schleiden in 1838 to detect the presence of cellulose and yet arrived at opposite conclusions, claiming that cellulose was not limited to the cell-walls (as in Schleiden’s model) but distributed evenly throughout the cell. Second, he challenged Schleiden’s very methods themselves by claiming that the cell boundaries Schleiden described were actually artifacts produced by his preparative techniques. In other words, Huxley seems to be saying that one 67 T. H. Huxley, 1853c, pp. 225, 226; 1898–1901, 1: 247, 249. 68 T. H. Huxley, 1853c, p. 229; 1898–1901, 1: 255. 69 T. H. Huxley, 1853c, p. 230; 1898–1901, 1: 256.
268
MARSHA L. RICHMOND
can freely use “chemical and mechanical” techniques in microscopy, but must be circumspect in drawing inferences from them.70 Huxley then bolstered these empirical results by appealing to Wolff’s views about the structure of plant tissues. Wolff had described vegetable tissue as “a homogeneous cellulose-yielding, transparent substance, containing cavities, in which lie peculiar vesicular bodies, into whose composition much nitrogen enters.” In Huxley’s view, it was these “cavities” that modern theorists had associated with “cells.” Yet they had invested them with properties that were not only speculative but also pernicious to the advancement of biology. Indeed, Huxley believed that the “cells” of cell theory were so infused with the assumption of anatomic individuality that it was necessary to introduce new terms to denote the various elements. In replacing the terms cell-wall, protoplasm, and nucleus, Huxley sought to revise the understanding of cellular constitutents such that the terms would express “nothing but their mutual relation,” that is, their function, not their structure. For the “homogeneous, cellulose-yielding, transparent substance” (protoplasm, cell wall/membrane, and intercellular substance) he chose the term “periplast,” while he labeled the “peculiar vesicular bodies” containing nitrogen (nucleus and similar membrane-bound elements) “endoplasts.”71 In so doing, as we shall see, Huxley focused attention on the role such elements played in histological development. Rather than stressing the centrality of the nucleus (endoplast) in cell life, as postulated by German cell theory, Huxley turned this notion on its head, placing a greater emphasis on the boundary area (periplast) of “cells.” Not only did Huxley continue to use these terms in preference to the more widely used designations throughout his career, but his later writings always emphasized cell contents or periphery as the active site of organic action rather than the nucleus. Such an approach can be seen in Huxley’s criticism of Schleiden’s view of the plant cell consisting of cell wall, contents, and nucleus. He pointed out that such an “enumeration of the elements of the vegetable-cell” was both inconsistent and incomplete. For one, it had been shown that many plant cells – including many algae, the leaf of sphagnum, and “young germinating Ferns” – contain “no trace of a nucleus.” Moreover, since the publication of Schwann’s book, von Mohl had discovered a new structure in vegetable cells, the so-called “primordial utricle.” Invariably present in young tissues, the primordial utricle was the “nitrogenous membrane, which always lies in close contact with the periplast, and forms, in fact, an included vesicle, within 70 Schickore draws attention to the difficult negotiations between technique and interpre-
tation that accompanied the introduction of experimentation into microscopic studies in the 1840s and 1850s (Schickore, 1999). 71 T. H. Huxley, 1853c. p. 230; 1898–1901, 1: 256.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
269
which the ‘contents’ and the nucleus lie.”72 Huxley considered this discovery of the greatest importance in challenging the model of the cell proposed by Schleiden and Schwann, for the presence of the primordial utricle in vegetable cells invalidated each of the enumerated assumptions concerning plant cell structure, and hence called into question the homology between vegetable and animals cells upon which the unified cell theory was based. Since then, the functions of the vegetable “cell” can be effectually carried on by the primordial utricle alone; since the “nucleus” has precisely the same chemical composition as the primordial utricle; and since, in some cases of cell-division, new nuclei are seen to arise in the substance of the endoplast, by a mere process of chemical and morphological differentiation . . . it follows, we think that the primordial utricle must be regarded as the essential part of the endoplast – the protoplasm and nucleus being simply its subordinate, and, we had almost said, accidental anatomical modifications.73 For those holding a morphological view of the cell, the primordial utricle could easily be incorporated into the accepted structural model, regarding it simply as an interior membrane associated with the cell wall in plants. Huxley, however, conceptualizing the cell in developmental terms, viewed the primordial utricle as representing a stage in plant cell development that had to have a corollary in the animal cell. This view called the morphological model of German cell theory into question. Finally, Huxley disputed Schleiden’s description of cell genesis. The production of new cells through “free-cell formation” (exogenous formation), assumed by both Schleiden and Schwann, was less prevalent than that of simple cell division. “The fact is, that in by far the greater proportion of cases, new cell-development occurs by the division of the previous endoplasts, and the growth or deposition round them and between them, of fresh periplastic substance.”74 It is interesting to note that Huxley’s view of cell division as a process involving a dividing “nucleus” and “cytoplasm” was in the vanguard of the “readjustment in the theoretical representation” of Schwann’s cell theory incorporated a few years later into Virchow’s revised cell theory.75 Yet Huxley’s notion of new cell formation, in contrast to that held by cell theorists, envisioned a passive nucleus that played no definitive role in cell genesis nor held any special meaning within histological differentiation. Indeed, the 72 Huxley cited von Mohl 1850 as well as Arthur Henfrey’s English translation (von Mohl, 1852). See also Pelz, 1987. 73 T. H. Huxley, 1853c, p. 231; 1898–1901, 1: 257. 74 T. H. Huxley, 1853c, p. 231; 1898–1901, 1: 258. See Duchesneau, 1987, pp. 246–249. 75 See Duchesneau, 1987, pp. 285–287.
270
MARSHA L. RICHMOND
production of new cells through division indicated to Huxley that the cell was not an anatomically independent unit but rather manifested genetic continuity with the whole organism: “the whole of the ‘cells,’ – the entirety of the periplasts and endoplasts – of which a plant, whether it be a moss or an oak, are composed, never are independent of one another, and never have been so, at any period of their existence; but that, while the original endoplast of the embryo-cell, from which the plant sprung, has grown and divided into all the endoplasts of the adult, the original periplast has grown at a corresponding rate, and has formed one continuous and connected envelope from the very first.” Hence, he concluded, “for the notion of the anatomical independence of the cells, we must substitute that of the unity and continuity of the periplastic substance in each case.”76 Huxley’s focus on the interconnection of the parts of which an organism is composed rather than their independence arose out of a conception of the organism that was developmental and epigenetic rather than reductionist and morphological. Having thus demonstrated that “every statement of Schleiden’s on which [Schwann] relied” was “erroneous,” Huxley next turned to the evidence Schwann adduced from animal tissues, particularly from his study of the structure of cartilage. At the outset, Huxley pointed out that Schwann’s fundamental assumption of the “identity of structure of plants and animals,” based on his belief that the nuclei of plant cells were morphologically and homologically equivalent to the nuclei of cartilage cells, was no longer viable. Von Mohl’s discovery of the primordial utricle in plant cells indicated that no such correlation existed. Since the endoplast of plant cells consisted of the entire primordial utricle, not simply the nucleus, the endoplast of animal cells was homologous with the “primordial utricle, contents and nucleus; or, in other words, that the ‘nucleus’ of cartilage is the equivalent of the ‘primordial utricle’ of the plant – that they are both endoplasts.”77 Next, Huxley compared Schwann’s descriptions of plant and cartilage cells with his own observations. Using similar chemical reagents to compare young sphagnum leaves with young cartilage, Huxley found that “in each, we see highly nitrogenous, more or less vesicular endoplasts imbedded in a homogeneous transparent substance, whose cavities they wholly fill.” That is, he saw Schwann’s nucleated cell. When he examined tissues that were slightly older (that is, had undergone further histological differentiation), although in sphagnum the endoplasts had increased in size, in some areas of the tissue he observed “regular primordial utricles without any nucleus.” Likewise in cartilage, “the endoplasts increase in size for a while, and then stop, while the periplastic cavities continue to increase, and thus we have 76 T. H. Huxley, 1853c, p. 231; 1898–1901, 1: 258. 77 T. H. Huxley, 1853c, p. 233; 1898–1901, 1: 260.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
271
eventually a cartilage cavity with its corpuscle.” This, again, was the nucleated cell described by Schwann. However, in “old cartilage,” Huxley found that the “corpuscle” (nucleus) “frequently disappears, or is converted into fat.” The organization that Huxley observed under the microscope, however, was not the same as that viewed by cell theorists. For example, he concluded that “the corpuscle does not correspond with the nucleus of the plant, as Schwann supposed, but with the primordial utricle, contents and nucleus; or, in other words, that the ‘nucleus’ of cartilage, is the equivalent of the ‘primordial utricle’ of the plant – that they are both endoplasts.” That is, there was no one-to-one correspondence between morphologically similar plant and animal cell structures; instead, similarity between the two resulted from the shared processes of development they exhibited. This observation thus proved Huxley’s point. “We are led, then, to the conclusion, that though Schwann’s great principle of the identity of structure of plants and animals is perfectly correct, his exposition of it is incorrect.” It was not empirical errors that led Schwann astray. Rather, his “structural errors,” Huxley believed, were based on erroneous theoretical assumptions, namely, “Schwann’s views of the nature and powers of the ‘cell,’ and those subsequently developed (principally by Kölliker) with respect to the action of the nuclei as ‘centres of force.’ ” Both of these assumptions ultimately derived, according to Huxley, from postulating the anatomical independence of cells, citing in support a long passage from Schwann’s book: We must, in fact, ascribe an independent life to cells – i.e., the combination of molecules which take place in a single cell are sufficient to set free the force, in consequence of which the cell has the power of attracting new molecules. The case of nutrition and growth lies not in the organism as a whole, but in the separate elementary parts – the cells. That in point of fact every cell, when separated from the organism, is not capable of further growth, as little militates against this theory, as its incapability of existing separate from the swarm would be an argument against the independent life of a bee. . . . The inquiry into the fundamental forces of organisms, therefore, is reduced into one concerning the fundamental forces of the single cells. (p. 229.) Such a view led Schwann to maintain “that the cell as such possesses powers which are not inherent in its separate molecules”; it also misled Kölliker into advocating “the existence of a peculiar molecular attraction proceeding from the nucleolus first, and subsequently from the nucleus” in order to explain the “phenomena of yelk-division and of endogenous cell-development.”78 78 T. H. Huxley, 1853c, pp. 233, 234; 1898–1901, 1: 261, 262.
272
MARSHA L. RICHMOND
To illustrate how Kölliker’s description of the process of yelk-division – “that remarkable manifestation of a tendency to break up, in the yelk of most animals, into successively smaller spheroids, in each of which a nucleus of some kind appears” – could be explained without recourse to “the effects of the force supposed to be exerted by the nuclei,” Huxley considered the descriptions investigators had recently given of segmentation of yelk in the early embryonic development in different animals. From these he concluded that the assumption of a central attractive force was neither sufficient nor necessary to explain the phenomena. For example, it failed to explain the “metabolic changes of the tissues,” since, as he subsequently showed, it was not the nucleus (endoplast) that was the primary site of future differentiation but the periplast. Organic vitality, Huxley asserted, comes not from any hypothetical cellforce, nuclear-force, or metabolic-force residing in organized structures within the homogeneous matter of the endoplast. Objecting to the mechanistic underpinnings of cell theory, he proclaimed that “the cells are not machines by which alone further development can take place,” nor should they be viewed, as Carpenter suggested, as “instrumental” to the process of development.79 “They are not instruments, but indications – that they are no more the producers of the vital phenomena than the shells scattered in orderly lines along the sea-beach are the instruments by which the gravitative force of the moon acts upon the ocean. Like these, the cells mark only where the vital tides have been, and how they have acted.” “Vital forces,” in other words, were simply “molecular forces.”80 Having shown that “there is no evidence that the ‘cells’ of living bodies are, in any respect, centres of those properties which are called vital forces,” Huxley next asked, Why, then, do similar structures – cells – appear in both plant and animal histology, if not by virtue of their central impor79 Carpenter, 1851, p. 737; Carpenter stated that in using the term “cell-force” he meant
“not that the force is produced or generated by the cell, but that the growth of the cell is the most general objective manifestation of that force, and that the cell affords the ordinary instrumental condition for its exertion, though there can be no doubt that the force may be exerted in many cases in which cell-development does not take place.” Correlating vital force with physical forces, Carpenter saw all as “emanating at once from the Divine Will” (p. 752). See also Carpenter, 1888, pp. 50–52, 173–184; Hall, 1979. 80 T. H. Huxley, 1853c, p. 243; 1898–1901, 1: 277, 278. Huxley appears to be referring to forces between chemical molecules rather than to “histological molecules,” or microscopically visible particles noted in blood, various tissues, and sometimes cells. For the currency of the concept of histological molecules at the time, particularly as represented in John Hughes Bennett’s “molecular theory” of disease and cell structure, see Strick, forthcoming, chap. 2. Huxley also thereby delineates his brand of scientific materialism from that of Carpenter, whose deistic tendencies match Desmond’s description of “physiological materialism.” See Desmond, 1989, pp. 5–6, n. 13.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
273
tance in the life of the organism? To answer this question, he developed his own “general theory” of the relationship between histological structure and organic development.
Huxley’s Epigenetic View of the Cell Describing histology as “only ultimate morphology,” Huxley proceeded to outline his views in a “general theory of the structure of plants and animals – conceived in the spirit, and not unfrequently borrowing the phraseology of Wolff and Von Baer.” This theory, which attempted to unify histology and embryogenesis, was based on a synthesis of von Baer’s views of embryogeny with Wolff’s doctrine of histological development.81 According to von Baer’s law of embryological development, the history of development “ ‘is the history of a gradually increasing differentiation of that which was at first homogeneous.’ ” Wolff also envisioned tissue structure as arising epigenetically out of an originally homogeneous germinal material. From an initially “clear, viscous, nutritive fluid, which possesses no organization of any kind, but is at most composed of globules,” Wolff described how cavities (or “cells”) arise that are not the cause of organization but rather “the visible results of the action of the organizing power inherent in the living mass, or what Wolff calls the vis essentialis.”82 Accordingly, in Huxley’s view development begins with the germ itself – the homogeneous blastema – out of which arises the first differentiated elements – endoplast and periplast – or the so-called “nucleated cell.” These cells are subsequently differentiated into the specialized tissues and organs of plants and animals. Thus, the entire life history of an organism is one dominated by development. Cells should thus not be considered the locus of organic vitality, as the Germans would have it, but “simply a fact in the history of their histological development – a histologically necessary stage . . . which has no more causal connexion with that which follows it, than the equally puzzling morphological necessity for the existence of a chorda dorsalis or of Wolffian bodies has with the development of the true vertebrae or of the true kidneys.”83 This alternative interpretation of the cell necessitated a revision in understanding the role of its various structural components. Rather than being the locus for cell development and metabolism, the nucleus (endoplast), consisting of homogeneous matter, was in fact the least important cell structure. It was the periplast that was histologically more significant, for 81 T. H. Huxley, 1853c, pp. 235, 236; 1898–1901, 1: 264, 266. 82 T. H. Huxley, 1853c, p. 228; 1898–1901, 1: 252. 83 T. H. Huxley, 1853c, p. 235; 1898–1901, 1: 265.
274
MARSHA L. RICHMOND
the periplastic substance subsequently differentiated, by means of chemical changes (through vacuolation and fibrillation), to form the various specialized structures of the body – tendon, muscle, bone, etc.84 To illustrate his views, Huxley referred his readers to figures illustrating cell structure in the leaf of sphagnum and the cartilage/tendon junction in a kitten. To enable a comparison between embryonic cells and differentiated tissues, histology required a general principle comparable to that of homology used in comparative anatomy. This Huxley found in Reichert’s “principle of continuity,” outlined in Ueber das Bindegewebe (1845), according to which “whatever histological elements pass into one another by insensible gradations are homologous and of the same nature.” The principle of continuity gave Huxley the means to contribute to the currently debated question concerning which portion of the cell differentiates in forming the different tissue types. In the case of the connective tissue that arises from cartilage, he claimed that the periplast of the embryonic cartilage cells underwent a chemical change to develop into intermediate tissue and then pure tendon, as shown by the different effects that acetic acid had on these parts. The endoplasts, on the other hand, “may elongate to some extent, but eventually become lost, and cease, more or less completely, to be distinguishable elements of the tissue” (see Figure 2).85 This evidence confirmed his view that the periplast was the more important element in cell life. As he expressed this idea in his April 1853 lecture, “In both Plants and Animals, then, there is one histological element, the Endoplast, which does nothing but grow and vegetatively repeat itself; the other element, the periplastic substance, being the subject of all the chemical and morphological metamorphoses, in consequence of which specific Tissues arise.”86 Cells, in other words, carried little morphological significance in the life of an organism, and nuclei were histologically less important than the cell periphery, including the protoplasm, cell wall, and intercellular substance. Huxley’s Rejection of the Unicellular Hypothesis Huxley’s criticism of German cell theory also forced him to re-evaluate his previous acceptance of the “unicellular” concept of protozoa. Even granting the tenets of cell theory, there arose difficulties, he noted, in applying this notion to “one-celled” plants and animals. “In the terms of the cell-theory, is not the cell supposed to be an anatomical and physiological unity capable 84 T. H. Huxley, 1853c, pp. 237–242; 1898–1901, 1: 268–276. 85 T. H. Huxley, 1853c, pp. 239–240; 1898–1901, 1: 271–272. Reichert was one of the few
Germans who opposed cell theory, adopting a more wholistic notion of the organism and also focusing more on “the nature of the protoplasm.” See Nyhart, 1995a, p. 88. 86 T. H. Huxley, 1853b, p. 301; 1898–1901, 1: 219.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
275
Figure 2.
of performing one function only – the life of the organism being the life of the separate cells of which it is composed? and is not a cell with different organs and functions something totally different from what we mean by a cell among the higher animals? We must say that the admission of the existence of unicellular organisms appears to us to be virtually giving up the cell-theory for these organisms.” Simple organisms, in other words, should be viewed as “acellular” rather than “unicellular.” Moreover, having worked out a systematic view that diminished the significance of cells in organic life, Huxley could no longer accept a unicellular concept that equated vitally active simple organisms with individual cells. According to his general theory, if “the histological differentiation into cells have no necessary causal connexion with the action of the vital forces, but be merely a genetic state, we may expect to meet with cases in which it does not occur. Such, in fact, are the so-called unicellular plants and animals – organisms which often exhibit no small complexity of external form, but
276
MARSHA L. RICHMOND
present no internal histological differentiation.” “If it be once admitted,” he continued, “that a particle of vitalizable matter may assume a definite and complex form, may take on different functions in its different parts, and may exhibit all the phenomena of life, without assuming the cellular structure, we think that it necessarily follows that the cells are not the centre of the manifestation of the vital forces; or that, if they be so, the nature of these forces is different in the lower organisms from what it is in the higher – a proposition which probably few would feel disposed to maintain.”87 Alluding to the controversial question about the relationship between the simplest forms of life and higher organisms, Huxley noted that if there were a similarity in the cellular structure of plants and animals, then there should also be a corresponding similarity in the early stages of embryonic development in invertebrates and vertebrates. This, however, was not the case. He thus implicitly denied, on histological as well as embryological grounds, any possibility for the transmutation of unicellular organisms into metazoa.
Underlying Factors Influencing Huxley’s “About-Face” on Cell Theory In “The Cell-Theory,” Huxley presented an alternative conception of the cell, one that presented a physiological rather than morphological interpretation of cell structure and development. His criticism of the Schleiden-Schwann cell theory can ultimately be traced to his philosophical opposition to the new version of “preformationism” it represented. By investing special powers in anatomical structures – the cell and nucleus – rather than regarding vitality as resulting from the action of molecular forces of the matter of which organisms are composed, German cell theory violated Huxley’s “epigenetic” understanding of development, applied at the microscopic level of histological organization. Such assumptions, ultimately derived from the belief in the unity of nature prevalent in Naturphilosophie and carried over into scientific zoology, conflicted with Huxley’s firm commitment to an empiricist methodology in science. Not altogether eschewing speculation, Huxley rather proclaimed that scientists should clearly delineate the theoretical principles upon which their views were based in order to enable others to decide whether they were “separately sound and convertible.”88 Accordingly, Huxley 87 T. H. Huxley, 1853c, p. 236; 1898–1901, 1: 265–266. 88 T. H. Huxley, 1853c, p. 226; 1898–1901, 1: 250: “We must build our theories, in these
days, as we do our houses: giving up all attempt at Cyclopean architecture, let us bethink ourselves rather of the convenience of our successors, who will assuredly alter, and perhaps pull them down, to suit the needs of their own age; and if we seek their gratitude, let us strive not so much to knit our materials firmly together (which will only give them more trouble and yield us less thanks), as to see that they are separately sound and convertible.”
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
277
brought forward both empirical evidence and close argument in support of his criticism of cell theory. Yet, I would argue, observational data were auxiliary to, not the focus of, Huxley’s review. Both Huxley and his German colleagues utilized similar microscopical techniques and exhibited similar diagrams, and yet derived from them opposing conclusions, The dispute was rather engendered by a clash between opposing metaphysical systems. Such an interpretation makes Huxley’s 1853 review of cell theory less enigmatic: it is best seen as a manifesto presenting an alternative functionalist view of the cell in place of the morphological conception underlying German cell theory, one in which a “preformed” structure – the nucleus – was posited as the ultimate source of organic vitality.89 For Huxley, development was not directed by any particular structure but proceeded epigenetically through the action of molecular forces residing in matter, by virtue of whose action an originally homogeneous germ material was gradually transformed into more specialized, differentiated elements. This was a differing vision of life than that presented in German cell theory. Attempting to avoid the assumption of a Lebenskraft, cell theorists endowed the nucleus with special powers governing both the life of the cell and that of the organism as a whole. Yet for Huxley such an assumption simply established the nucleus as a new vitalistic archon. The radical shift in Huxley’s position on both cell theory and the unicellular hypothesis that took place between 1851 and 1853 nonetheless presents the historian with a dilemma. Certainly, as we have seen, Huxley may have been prompted by his close study of modern cell doctrine, especially as presented in Kölliker’s treatise, to realize that the empirical as well as philosophical underpinnings of German cell theory were opposed to his own understanding of biological organization. Yet his decision to publish an opposing “general theory of the structure of plants and animals,” one directed at a broad readership, may also have been prompted by synergistic factors that climaxed during this crucial two-year period. Between the appearance of his paper on Thalissicolla and the review of cell theory, Huxley published a paper in 1852 on the morphology of the 89 Roe, 1981, pp. 148–149. Although calling cell theory “a great watershed for the teleomechanist research program,” Lenoir also recognized the dilemma such a morphological interpretation posed, for “in identifying the seat of development with a specific set of structures the ever-present question of the limits of mechanical explanations in biology stepped once again to the foreground” (Lenoir, 1989, p. 114). In the British context, the ongoing question of the relationship between matter and force was also problematic. See, for example, Winter, 1997, pp. 36–39; Jacyna, 1983. For a consideration of how historians might analyze the political context associated with physiological theories of histological structure – ranging from those positing extreme centralization to complete devolution and according to the degree of functional differentiation they assume – see Pickstone, 1999.
278
MARSHA L. RICHMOND
tunicates, in which he first presented his theory of animal individuality. This theory was offered as an alternative to both Johannes Japetus Steenstrup’s controversial theory of the alternation of generations and Owen’s rival theory of parthenogenesis.90 By suggesting that morphologically different generations of one species form a single, extended “individual” or “zooid,” Huxley would find it difficult to espouse a unicellular concept in which individuality and “cellularity” were accorded to a comparable single, morphologically differentiated form. If a zooid, like a protozoon, could assume a “definite and complex form,” take on “different functions in its different parts,” and “exhibit all the phenomena of life, without assuming the cellular structure,” then like zooids, neither cells nor protozoa could be granted “individuality.”91 Huxley’s rejection of endogenous development in favor of cell division may also have been linked to his concept of individuality. As John Farley has pointed out, theories of “free cell formation” like Schwann’s and Kölliker’s formed the basis for ideas of animal and plant individuality. “If the cell never divided but always propagated by endogenous or exogenous free cellformation, the cell itself was the indivisible unity, the true individual.”92 Given his newly formulated views on individuality, Huxley obviously could not accept such as assumption. Generation by division reinforced genetic continuity. Second, it may not be entirely coincidental that Huxley’s rejection of the unicellularity concept also served to bolster evidence against transmutation. As Adrian Desmond and others have shown, the idea of transmutation of species was considered scientifically suspect and socially pernicious prior to the publication of Darwin’s theory of evolution. Certainly, in his review of the tenth edition of Vestiges of the Natural History of Creation (1853), Huxley focused particular derision on the “monad to man” passage, in which Chambers outlined the gradual transmutation of a unicellular organism into an analogous “unicellular” egg cell that developed into the mammal itself.93 90 See T. H. Huxley, 1851c and 1852. As di Gregorio has pointed out, “[Huxley’s] early
work on Salpa, overtly arguing against Chamisso, was covertly an attack on Owen’s notions of parthenogenesis, and was appreciated as such by Allman and Darwin” (di Gregorio, 1984, p. 187). 91 See T. H. Huxley, 1851a, 1851d, and 1852. For a good account of Huxley’s philosophical speculation about animal individuality, see J. Huxley, 1936, pp. 51–52. Nyhart has also connected Huxley’s rejection of cell theory to his developmentalist views on animal individuality (Nyhart, 1995b). 92 Farley, 1982, p. 88. 93 Drawing upon Carpenter’s 1842 paper on cells and Barry’s 1843 article on fissiparous generation, Chambers compared the mammalian ovum to the “young of the infusory animalcules” and concluded that “all animated nature may be said to be based on this mode of origin; the fundamental form of organic being is a globule, having a new globule forming within itself, by which it is in time discharged, and which is again followed by another and another, in
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
279
One year later, Huxley pointedly attempted to undermine “progressionist” notions by disputing the evidence for progress in the fossil record.94 Although the transmutationist connotations of the unicellular hypothesis may not have initially occurred to Huxley, they were certainly not lost on the Edinburgh anatomist John Goodsir. In his medical lectures delivered in the 1850s, Goodsir identified the nucleated cell as the “protozoan type of organization” and described the structure of a unicellular organism as representing “potentially the typical structure of the entire Animal Kingdom.” Huxley may have come to understand, as Jacyna has pointed out, that a biologist’s “cellular reality” was framed by particular philosophical and social presuppositions.95 Third, Huxley’s commitment to establishing a methodological reform in British natural history also served social ends. In the 1850s he and a cohort of like-minded colleagues were increasingly involved in promoting reform in British science in which, as in the movement associated with wissenschaftliche Zoologie in Germany, the establishment of exact scientific methodology was central.96 Only by establishing rigorous requirements for explanation could biology achieve recognition as a profession, with expanding career opportunities for its practicioners. Huxley and other members of this group likewise promoted more stringent criteria for membership in scientific societies; new avenues for publishing morphological studies, culminating in Huxley’s assuming the editorship of the Natural History Review in 1860; and an expanded role for biology in both the university and school curricula.97 Yet prior to his 1854 appointment as lecturer in natural history at the Government School of Mines, Huxley’s particular interest in establishing a reputation based not only on his scientific researches but also on his advocacy of a truly endless succession.” See Chambers, 1994, pp. 172–173; Secord, 1994, p. xxxiv. See also T. H. Huxley, 1854, p. 341. Quoting from this passage in Vestiges, Huxley singled out the sentence, “The volvox globator can hardly be distinguished from the germ which, after passing through a long foetal progress, becomes a complete mammifer, an animal of the highest class,” and added: “[!!!].” See also di Gregorio, 1984, pp. 48–50. 94 T. H. Huxley, 1855. See also Desmond, 1995, pp. 191–194; Lyons, 1995; Lyons, 1999. 95 Jacyna, 1983b, p. 87. The denial of unicelluarity and, as Strick has stressed, of exogenous cell division, undermined support for abiogenesis (Strick, forthcoming, chap. 2). According to Ilse Jahn, Ehrenberg well realized that his view of protozoa as complete organisms undermined both transmutation and abiogenesis (Jahn, 1982, p. 354). 96 Cardwell, 1972; Cannon, 1978. Darwin and Hooker also decried the overly speculative vein in German science and transcendental morphology. Like Huxley, Darwin rejected Owen’s assumption of a “spermatic force” to explain parthenogenesis and also Forbes’s “principle of polarity,” which he said made him “sick – it is like ‘magnetism’ turning a table.” Hooker, for his part, told Darwin in 1854, after reading Alexander Braun’s botanical theory of “rejuvenescence,” that he was “very sick of German phantasies.” See Darwin, 1985–, 6: 484, and 5: 201, 206. On reform in Germany, see Nyhart, 1996, chap. 3. 97 Barton, 1998.
280
MARSHA L. RICHMOND
“scientific” morphology may have been especially acute. Such a perspective better explains Huxley’s increasingly accrimonious conflict with Owen after 1854 – that is, a disagreement as much grounded in methodological differences and connected with institutional and professional rivalry as in personal animosity.98 To establish a truly scientific methodology for morphology, Huxley had to confront the remnants of Naturphilosophie, not only in transcendental morphology but also in cell theory and wissenschaftliche Zoologie. Such concerns are evident in remarks Huxley made to Darwin in 1857. Responding to Darwin’s assertion that linking classification to genealogy would “make the difference between analogy and homology, clear,” Huxley countered that he considered the root of the problem in British natural history studies was rather the failure of naturalists to adopt the morphological methodology of scientific zoology: I for one believe that a Scientific and logical Zoology and Botany are not at present possible – for they must be based on sound Morphology – a Science which has as yet to be created out of the old Comparative Anatomy – and the new study of Development. When the mode of thought and speculation of Oken and Geoffroy S. Hilaire and their servile follower Owen, have been replaced by the principle so long ago inculcated by Caspar Wolff and Von Baer and Rathke – and so completely ignored in this country and in France up to the last ten years – we shall have in the course of a generation a science of Morphology and then a Scientific Zoology and Botany will flow from it as Corollaries –99 Huxley thus aimed to introduce scientific zoology into Britain – shorn of questionable metaphysical assumptions and reformulated to present an epigenetic approach to organization extending even to the level of “ultimate histology” – the “cell.”
The Legacy of “The Cell-Theory” Huxley’s contemporaries certainly detected the message carried by “The Cell-Theory.” As Carpenter admitted in his presidential lecture to the members of the Microscopical Society in 1856, although he was “not by any 98 Desmond makes the same point, suggesting that the root cause of Huxley’s and Owen’s opposition was ideological and contrasting Owen’s Anglicized version of transcendental and romantic morphology with what he simply calls Huxley’s “positive approach.” See Desmond, 1982, chap. 1 and p. 40. 99 See Darwin’s letter to T. H. Huxley, 26 September [1857], and the letter from T. H. Huxley, [before 3 October 1857], in Darwin, 1985 –, 6: 456, 461.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
281
means disposed to go as far as Mr. Huxley in abandoning the cell-doctrine of Schwann and his followers,” he could not “but admit the correctness of much that he was urged.” “The essential truth, however, seems to me to lie between the two extremes; in other words the cell-doctrine of Schwann can only be accepted when the word ‘cell’ is understood in a sense much wider than that to which he limited it; but when it has been thus modified there does not seem to me to be any adequate reason for relinquishing it.”100 The following year, the new president George Shadbolt noted that three papers published by the society that year tended “to controvert the cell-theory of Schleiden and Schwann,” primarily their views on cell division.101 Hence, Huxley was not the only British naturalist who had doubts about the tenets of cell theory. Others also demurred to the overly theoretical nature of German investigators. The highly respected amateur microscopist, F. H. Wenham, for example, objected to the “technical phraseology” found in continental cytological literature. The use of such specialist jargon, in his view, not only was a “mistaken display of scientific pedantry” calculated to confuse “the uninitiated,” but it also encouraged errors in interpretation. Led by theory to “see” an “imaginary substance,” investigators could get caught up in “a maze of hypotheses.” Such, he believed, was the case with the accepted view of vegetable cell formation, which held that it proceeded from the central nucleus, or “cytoblast,” around which a “primordial utricle” formed. Those microscopists who, like myself, experience the most fervent delight in reading a page directly from the book of nature, may resort to their microscopes again and again in the hope of witnessing the first creation of the vegetable cell, in relation to the acting conditions of the cytoblast and primordial utricle. The search may be carried from tree, shrub, flowers, or fruit, and be alike in vain. No direct ocular evidence will be obtained of the existence of this nucleus and membrane, and the attempt is abandoned at last, perhaps not without some feelings of humiliation at the supposed unskilful manipulation, that failed to discover facts, believed to have been firmly established.102 At a time when microscopical technique was still in its infancy, when there was a limited means for differential staining and preserving specimens, when 100 Carpenter, 1856b, p. 23. 101 Shadbolt, 1857, p. 137. The papers were: F. H. Wenham, “On the Vegetable Cell,” Norris
F. Davey, “Brief Remarks upon Cell-Growth in the Bryonia dioica,” and Sidney Godolphin Osborne, “Vegetable Cell-Structure and its Formation, As Seen in the Early Stages of the Growth of the Wheat Plant.” 102 Wenham, 1856, pp. 1, 2.
282
MARSHA L. RICHMOND
only rough microtomes for sectioning were available, and before the introduction of oil-immersion lenses, theory was a powerful tool for guiding the observer. Indeed, professional biologists, like Carpenter and Huxley, frequently lamented the overly empirical tendency of British amateur microscopists, attempting to direct them to studies that could best contribute to the advancement of biological research.103 Whereas Huxley may have agreed with Wenham’s criticism in principle, his enterprise was different. He wanted to engage with German theoretical constructs, not simply avoid them. A different attack on cell theory came from the Edinburgh physiologist John Hughes Bennett, who developed a theory of histological organization based on the concept of histological molecules rather than cells. First sketched in 1859 and further elaborated in a series of publications in the 1860s, Bennett’s theory attracted the attention of “a wide audience of researchers with biological and medical concerns.”104 Yet as Bennett well recognized, his views were both theoretically and empirically at odds with those held by Huxley. The continued currency of Huxley’s views in subsequent decades is shown by the prominent place accorded to them in James Tyson’s The Cell Doctrine (1870). In a work designed to instruct medical and dental students about current cell theory, Tyson outlined the main points of Huxley’s 1853 review and connected them to Huxley’s recent, widely discussed pronouncements in “On the Physical Basis of Life” (1869). Rather than contradicting his earlier views, as many assumed, Tyson believed Huxley’s identification of the protoplasm as the locus of vitality was “foreshadowed” in the 1853 essay.105 Although he described the structural unit of the human body as “a nucleated mass of protoplasm,” Huxley denigrated the role the nucleus played in cell life, as evidenced by his famous dictum: “Protoplasm, simple or nucleated, is the formal basis of all life.”106 Indeed, in his article on biology published in the ninth edition (1878) of the Encyclopaedia Britannica, Huxley still asserted that “in the animal, as in the plant, neither cell-wall nor nucleus are essential constitutents of the cell, inasmuch as bodies which are unquestionably the equivalents of cells – true morphological units – are masses of protoplasm, devoid alike of cell-wall and nucleus,” and noted that “the process of development of the animal or the plant from its primary egg or germ is a true process of evolution – a progress from almost formless to more or less highly organised matter, in virtue of the properties inherent in that
103 See Carpenter, 1856a. See also Carpenter, 1856b; T. H. Huxley, 1879. 104 Strick, forthcoming, chap. 2. 105 Tyson, 1870, pp. 48–54. 106 T. H. Huxley, 1870, pp. 14, 16. See also Geison, 1969.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
283
matter.”107 Hence, he continued to hold views developed twenty-five years earlier. In assessing Huxley’s scientific work after his death, both Michael Foster and E. Ray Lankester mentioned the impact “The Cell-Theory” had on young British biologists. Foster drew attention to the methodological importance of Huxley’s piece, stating that it “drove the sword of rational inquiry through the heart of conceptions, metaphysical and transcendental, but dominant.” Lankester called the review “a fundamental study in Morphology” and claimed that after forty years and immense progress in cytology, Huxley’s views still had currency among many biologists. “The main contention of that article, viz. that cells are not the cause but the result of organisation,” he stated, “is even now being reasserted, and in a slightly modified form is by very many cytologists admitted as having more truth in it than the opposed view and its later outcomes, to the effect that the cell is the unit of life in which and through which alone living matter manifests its activities.”108 Lankester may have been referring to the recent criticisms of German cell theory by the Cambridge morphologist Adam Sedgwick and the American zoologist Charles Otis Whitman, both of whom advanced “epigenetic” conceptions of the cell.109 Sedgwick, Francis Maitland Balfour’s successor as head of the Cambridge school of morphology, indeed illustrates the continuing hold that Huxley’s views exerted on the research program in evolutionary physiology and embryology at Cambridge University.110 It is thus not surprising to find that the most vocal opposition to the neopreformationism represented by August Weismann’s theory of heredity, based on his notion of the continuity of the germ plasm and the predominance of the nucleus in cell life, came from biologists trained at Cambridge. Indeed, Sedgwick’s student, C. Clifford Dobell, continued well into the twentieth century to deride views of the centrality of the nucleus (Kernmonopol) in cell life and the unicellular concept of protozoa.111 Thus, the epigenetic and physiological conception of cells that Huxley formulated in 1853, although certainly based, as historians of cytology have noted, on erroneous empirical interpretations, nonetheless held profound philosophical, methodological, and social implications for the future devel107 T. H. Huxley, 1878, p. 682, and 1880. 108 L. Huxley (ed.), 1913, 1: 203. 109 Whitman cited a passage from Huxley’s “The Cell-Theory” in his article “The Inadequacy of the Cell-Theory of Development” (Whitman, 1894). See also Sedgwick, 1894. On Sedgwick and his Cambridge followers, see Richmond, 1989, and in preparation. 110 See Geison, 1978; Ridley, 1985; Richmond, 1997. 111 Both Sedgwick and Sydney Howard Vines, a reader in physiological botany at Cambridge prior to his appointment as professor of botany at Oxford, were vocal opponents of Weismannism in England. See, for example, Vines, 1889. See also Richmond, 1989.
284
MARSHA L. RICHMOND
opment of British morphology. His views about histological organization influenced future generations of biologists to see the cell, as well as the developing organism, as part of an overriding process of epigenesis.112 Yet Huxley did not entirely eschew preformationism; rather, he believed his interpretation united, as he stated in a paper of 1861, “the theories of the preexistence of germs with that of epigenesis.”113 The scientific methodology he espoused, bolstered by examples provided by his publications and those of like-minded biologists, helped in the years before the publication of Origin of Species to introduce a new generation to a “scientific” zoology that sought to exclude remnants of transcendentalism within morphological research.114 After embracing Darwin’s theory of evolution in 1859, Huxley and his cohort contributed to incorporating tenets of scientific zoology into the new program of evolutionary morphology.115 Against the backdrop of the changing social, institutional, and political landscape in Britain in the late 1840s and early 1850s, then, Huxley’s early writings illustrate how methodology could carry multifaceted meanings within the realm of science.
Acknowledgments This article greatly benefited from the critical comments of a number of people, including Jane Maienschein, Garland Allen, Adrian Desmond, and two anonymous reviewers. I would also like to thank Soraya de Chadarevian, Mario di Gregorio, Anne Mylott, Lynn Nyhart, Jim Secord, Judy Johns Schloegel, Jim Strick, and my former colleagues on the Darwin Correspondence Project – Janet Browne, Anne Secord, Joy Harvey, Thomas Junker, and Steve Pocock – for many engaging and enjoyable conversations about Huxley, scientific zoology, and British and German biology in the 1850s and 1860s. Research for this project was in part funded by a grant from the Office of Research and Sponsored Programs, Wayne State University.
112 See Gooday, 1991. 113 T. H. Huxley, 1861. 114 As Philip Rehbock has pointed out (Rehbock, 1983, pp. 6, 195), “The publication of On the Origin of Species in 1859, though typically treated as the commencement of a new epoch in the theory of natural history, was in fact the climax of half a century of searching for the philosophical foundations of the new science, ‘biology.’ ” 115 In Germany, it was Haeckel who synthesized the tradition of scientific zoology with evolution theory (Nyhart, 1995a, p. 168).
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
285
References Anonymous. 1891. “Thomas Wharton Jones.” British Medical Journal 2: 1175–1177. Baker, John R. 1988. The Cell Theory. A Restatement, History, and Critique. Rpt. edn. New York and London: Garland. Barry, Martin. 1837. “On the Unity of Structure in the Animal Kingdom.” Edinburgh New Philosophical Journal 22: 116–141. —— 1837. “Further Observations on the Unity of Structure in the Animal Kingdom, and on Congenital Anomalies, including ‘Hermaphrodites’; With Some Remarks on Embryology, as Facilitating Animal Nomenclature, Classification, and the Study of Comparative Anatomy.” Edinburgh New Philosophical Journal 22: 345–364. —— 1838. “Researches in Embryology. First Series.” Philosophical Transactions of the Royal Society 2: 302. —— 1847. “On the Nucleus of the Animal and Vegetable ‘Cell.’ ” Edinburgh New Philosophical Journal 43: 201–229. Barton, Ruth. 1998. “Huxley, Lubbock, and Half a Dozen Others: Professionals and Gentlemen in the Formation of the X Club, 1851–1864.” Isis 89: 410–444. Baxter, Alice Levine. 1976. “Edmund B. Wilson as a Preformationist: Some Reasons for His Acceptance of the Chromosome Theory.” Journal of the History of Biology 9: 29–57. Bracegirdle, Brian. 1978. A History of Microtechnique. Ithaca, NY: Cornell University Press. Buchdahl, Gert. 1973. “Leading Principles and Induction: The Methodology of Matthias Schleiden.” In Foundations of Scientific Method, ed. R. N. Giere and R. S. Westfall, pp. 32–52. Bloomington: Indiana University Press. Cannon, Susan Faye. 1978. Science in Culture: The Early Victorian Period. New York: Dawson and Science History Publications. Cardwell, D. S. L. 1972. The Organisation of Science in England. London: Heinemann. Carpenter, William Benjamin. 1837. “On Unity of Function in Organized Beings.” Edinburgh New Philosophical Journal 23: 92–114. —— 1840. “Schwann and Schleiden on the Identical Structure of Plants and Animals.” British and Foreign Medico-Chirurgical Review 9: 495–528. —— 1851. “On the Mutual Relations of the Vital and Physical Forces”. Philosophical Transactions of the Royal Society pt. 2: 727–757. —— 1856a. The Microscope and its Revelations. London. —— 1856b. “President’s Address.” Quarterly Journal of Microscopical Science 4: 17–33. —— 1888. Nature and Man: Essays Scientific and Philosophical, ed. J. E. Carpenter. London. Chambers, Robert. 1994. Vestiges of the Natural History of Creation and Other Evolutionary Writings, ed. James A. Secord. Chicago: University of Chicago Press. Churchill, Frederick B. 1989. “The Guts of the Matter. Infusoria from Ehrenberg to Bütschli: 1838–1876.” Journal of the History of Biology 22: 189–213. —— 1991. “The Rise of Classical Descriptive Embryology.” In A Conceptual History of Modern Embryology, ed. Scott Gilbert. New York/London: Plenum Press. Coleman, William. 1965. “Cell, Nucleus, and Inheritance: An Historical Study.” Proceedings of the American Philosophical Society 109: 124–158. —— 1971. Biology in the Nineteenth Century: Problems of Form, Function, and Transformation. New York: John Wiley & Sons. Darwin, Charles. 1985–. Correspondence of Charles Darwin, ed. F. H. Burkhardt et al., 11 vols. to date. Cambridge: Cambridge University Press. Desmond, Adrian. 1982. Archetypes and Ancestors, Palaeontology in Victorian London, 1850–1875. London: Blond and Briggs.
286
MARSHA L. RICHMOND
—— 1989. The Politics of Evolution: Morphology, Medicine, and Reform in Radical London. Chicago and London: University of Chicago Press. —— 1997. Huxley: From Devil’s Disciple to Evolution’s High Priest. Reading, MA: AddisonWesley. Duchesneau, François. 1987. Genèse de la Théorie Cellulaire. Montreal: Bellarmin/Paris: Vrin. —— 1994. “Kölliker and Schwann’s Cell Theory.” In La Storia della Medicina e della Scienza tra Archivio e Laboratorio, ed. Guido Cimino and Carlo Maccagni, pp. 103–121. Florence: Leo S. Olschki. Ehlers, Ernst. 1885. “Carl Theodor Ernst von Siebold. Eine biographische Skizze.” Zeitschrift für wissenschaftliche Zoologie 42: i–xxiii. Farley, John. 1982. Gametes and Spores: Ideas About Sexual Reproduction, 1750–1914. Baltimore: Johns Hopkins University Press. Forbes, Edward. 1848. A Monograph of the British Naked-Eyed Medusae. London. Foster, Michael. 1895. “A Few More Words on Thomas Henry Huxley.” Nature 52: 319. Geison, Gerald L. 1969. “The Protoplasmic Theory of Life and the Vitalist-Mechanist Debate.” Isis 60: 273–292. —— 1978. Michael Foster and the Cambridge School of Physiology. Princeton: Princeton University Press. Gooday, Graeme. 1991. “ ‘Nature’ in the Laboratory: Domestication and Discipline with the Microscope in Victorian Life Science.” British Journal for the History of Science 24: 307– 341. di Gregorio, Mario. 1984. T. H. Huxley’s Place in Natural Science. New Haven, CT: Yale University Press. —— with the assistance of Nick Gill. 1990. Charles Darwin’s Marginalia, Vol. 1. New York and London: Garland Publishing. Gould, Stephen Jay. 1977. Ontogeny and Phylogeny. Cambridge, MA: Harvard University Press. Haeckel, Ernst. 1866. Generelle Morphologie der Organismen. Berlin. Haines, George. 1957. German Influence Upon English Education and Science, 1800–1866. New London, CT. Hall, Vance. 1979. “The Contribution of the Physiologist, William Benjamin Carpenter (1813– 1885) to the Development of the Correlation of Forces and the Conservation of Energy.” Medical History 23: 129–155. Harris, Henry. 1999. The Birth of the Cell. New Haven, Conn.: Yale University Press. Hollowday, Eric D. 1995. “Thomas Henry Huxley and the Microscope.” Quekett Journal of Microscopy 37: 437–454. Hughes, Arthur Frederick William. 1959. A History of Cytology. New York: AbelardSchuman. Huxley, Leonard, ed. 1913. Life and Letters of Thomas Henry Huxley, 2nd edn., 3 vols. London: Macmillan. Huxley, Julian S. 1936. T. H. Huxley’s Diary of the Voyage of H.M.S. Rattlesnake. Garden City, NY: Doubleday, Doran & Co. Huxley, Thomas Henry. 1845. “On a Hitherto Undescribed Structure in the Human Hair Sheath.” London Medical Gazette 1: 1340. —— 1851a. “Observations Upon the Anatomy and Physiology of Salpa and Pyrosoma.” Philosophical Transactions of the Royal Society 2(1): 51–53. —— 1851b. “On the Auditory Organs in the Crustacea.” Annals and Magazine of Natural History 2nd ser. 7: 374.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
287
—— 1851c. “Zoological Notes and Observations Made on Board H.M.S. Rattlesnake During the Years 1846–1850. Pt. 3: Upon Thalassicolla, a New Zoophyte.” Annals and Magazine of Natural History 2nd ser. 8. —— 1851d. “Report upon the Researches of Prof. Müller into the Anatomy and Development of the Echinoderms.” Annals and Magazine of Natural History 2nd ser. 8: 1–19. —— 1852. “Upon Animal Individuality.” Proceedings of the Royal Institution of Great Britain 1 (1851–1854), 184–189. —— 1853a. “On the Morphology of the Cephalous Mollusca, as Illustrated by the Anatomy of Certain Heteropoda and Pteropoda Collected during the Voyage of H.M.S. Rattlesnake in 1846–50.” Philosophical Transactions of the Royal Society 1. —— 1853b. “On the Identity of Structure of Plants and Animals.” Proceedings of the Royal Institution of Great Britain (1851–1854) 1: 298–302; Edinburgh New Philosophical Journal 53: 172–177. —— 1853c. “The Cell-Theory.” British and Foreign Medico-Chirurgical Review 12: 285–314. —— (trans.). 1853. “Fragments Relating to Philosophical Zoology. Selected from the Works of K. E. von Baer.” In Scientific Memoirs, Selected from the Transactions of Foreign Academies of Science, and From Journals. Natural History, ed. Arthur Henfrey and T. H. Huxley. London. —— 1854. Review of Vestiges of the Natural History of Creation, 10th edn. London; 1853. British and Foreign Medico-Chirurgical Review 13: 341. —— 1855. “On Certain Zoological Arguments Commonly Adduced in Favour of the Hypothesis of the Progressive Development of Animal Life in Time.” Proceedings of the Royal Institution of Great Britain (1854–1858) 2: 82–85. —— 1861. “On the Nature of the Earliest Stages of the Development of Animals.” Proceedings of the Royal Institution of Great Britain (1858–1862) 3: 315–317. —— 1870. On the Physical Basis of Life. New Haven, CN: Charles C. Chatfield. —— 1878. “Biology.” Encyclopaedia Britannica, 9th edn., Vol. 3, pp. 679–690. New York: Charles Scribner’s Sons. —— 1879. “President’s Address.” Journal of the Quekett Microscopical Club 4: 374–379. —— 1880. “The Coming of Age of the Origin of Species.” Nature 22: 1–4. —— 1898–1901. The Scientific Memoirs of Thomas Henry Huxley, ed. Michael Foster and E. Ray Lankester, 4 vols. + supplement. London: Macmillan. Jacyna, L. S. 1983a. “Immanence or Transcendence: Theories of Life and Organization in Britain, 1790–1835.” Isis 74: 311–329. —— 1983b. “John Goodsir and the Making of Cellular Reality.” Journal of the History of Biology 16: 75–99. —— 1984. “The Romantic Programme and the Reception of Cell Theory in Britain.” Journal of the History of Biology 17: 13–48. Jahn, Ilse. 1982. “Die Herausbildung zoologischer Disziplinen.” In Geschichte der Biologie. Theorien, Methoden, Institutionen, Kurzbiographien, ed. Ilse Jahn, Rolf Löther and Konrad Senglaub, pp. 344–395. Jena: Gustav Fischer Verlag. Jahn, Ilse, Rolf Löther and Konrad Senglaub, eds. 1982. Geschichte der Biologie. Theorien, Methoden, Institutionen, Kurzbiographien. Jena: Gustav Fischer Verlag. Kölliker, Albert. 1845. “Die Lehre von der thierischen Zelle und den einfacheren thierischen Formelementen, nach den neuesten Fortschritten dargestellt.” Zeitschrift für wissenschaftliche Botanik 1(2): 46–102. —— 1853–1854. Manual of Human Histology (trans., T. H. Huxley and George Busk), 2 vols. London.
288
MARSHA L. RICHMOND
Körner, Hans. 1967. “Carl Theodor v. Siebold (1804–1885).” In Die Würzburger Siebold. Leipzig. Lenoir, Timothy. 1989. The Strategy of Life: Teleology and Mechanics in Nineteenth-Century German Biology, 2nd edn. Chicago: University of Chicago Press. Lyons, Sherrie L. 1995. “The Origins of T. H. Huxley’s Saltationism: History in Darwin’s Shadow.” Journal of the History of Biology 28: 465–466. —— 1999. Thomas Henry Huxley: The Evolution of a Scientist. Amhurst, NY: Prometheus Books. von Mohl, Hugo. 1850. Die Vegetabilische Zelle. Braunschweig. —— 1852. The Vegetable Cell (trans., Arthur Henfrey). London. Nyhart, Lynn K. 1991. “Writing Zoologically: The Zeitschrift für Wissenschaftliche Zoologie and the Zoological Community in Late Nineteenth-Century German.” In The Literary Structure of Scientific Argument: Historical Studies, ed. Peter Dear, pp. 43–71. Philadelphia: University of Pennsylvania Press. —— 1995a. Biology Takes Form: Animal Morphology and the German Universities, 1800– 1900. Chicago: University of Chicago Press. —— 1995b. “ ‘A Difficult Subject’: Animal Individuality and Biological Politics, 1845–1860.” Paper Presented at the British Society for the History of Science Conference. T. H. Huxley: Victorian Science and Culture. London. Ospovat, Dov. 1976. “The Influence of Karl Ernst von Baer’s Embryology, 1828–1859: A Reappraisal in Light of Richard Owen’s and William B. Carpenter’s ‘Palaeontological Application of ‘Von Baer’s Law.’ ’ ”. Journal of the History of Biology 9: 1–28. Owen, Richard. 1843. Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animals. London. Pelz, Willy. 1987. Zellenlehre: Der Einfluss Hugo von Mohls auf die Entwicklung der Zellenlehre. Frankfurt am Main: Lang. Pickstone, John V. 1999. “How Might We Map the Cultural Fields of Science? Politics and Organisms in Restoration France.” History of Science 37: 347–364. Rehbock, Philip F. 1983. The Philosophical Naturalists: Themes in Early Nineteenth-Century British Biology. Madison: University of Wisconsin Press. Richards, Eveleen. 1987. “A Question of Property Rights: Richard Owen’s Evolutionism Reassessed.” British Journal for the History of Science 20: 129–171. Richards, Robert. 1992. The Meaning of Evolution: The Morphological Construction and Ideological Reconstruction of Darwin’s Theory. Chicago: University of Chicago Press. Richmond, Marsha L. 1988. “Darwin’s Study of the Cirripedia.” In Correspondence of Charles Darwin, ed. F. H. Burkhardt et al., Vol. 4, pp. 388–409. Cambridge: Cambridge University Press. —— 1989. “Protozoa as Precursors of Metazoa: German Cell Theory and its Critics at the Turn of the Century.” Journal of the History of Biology 22: 243–276. —— 1997. “ ‘A Lab of One’s Own’: The Balfour Laboratory for Women at Cambridge University, 1884–1914.” Isis 88: 222–255. —— In preparation. “Revolt Against Recapitulation: Adam Sedgwick and the Cambridge School of Morphology.” Paper Presented at the Sessions in honor of Frederick B. Churchill, International Society for the History, Philosophy, and Social Studies of Biology Meeting. Seattle, 1997. Ridley, Mark. 1985. “Embryology and Classical Zoology in Great Britain.” In A History of Embryology, ed. T. J. Horder, J. A. Witkowski and C. C. Wylie, pp. 35–68. Cambridge: Cambridge University Press.
HUXLEY’S CRITICISM OF GERMAN CELL THEORY
289
Rinard, Ruth. 1981. “The Problem of the Organic Individual: Ernst Haeckel and the Development of the Biogenetic Law.” Journal of the History of Biology 14: 249–275. Roe, Shirley A. 1981. Matter, Life, and Generation: Eighteenth-Century Embryology and the Haller-Wolff Debate. Cambridge and New York: Cambridge University Press. Rupke, Nicolaas A. 1993. “Richard Owen’s Vertebrate Archetype.” Isis 84: 231–251. Russell, Edward Stuart. 1917. Form and Function. A Contribution to the History of Animal Morphology. New York: E.P. Dutton. Schickore, Jutta. 1999. “The Use and Abuse of Chromium Acid.” Paper Presented at the International Society for History, Philosophy, and Social Studies of Biology Meeting. Oaxaca, Mexico. Schwann, Theodor. 1839. Mikroskopische Untersuchungen über die Übereinstimmung in der Struktur und im Wachstum der Thiere und Pflanzen. Berlin. —— 1847. Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants (trans., Henry Smith). London. Secord, James A. 1994. “Introduction.” In Vestiges of the Natural History of Creation and Other Evolutionary Writings by Robert Chambers, ed. James A. Secord. Chicago: University of Chicago Press. Sedgwick, Adam. 1894. “On the Inadequacy of the Cellular Theory of Development, and on the Early Development of Nerves, Particularly of the Third Nerve and of the Sympathetic in Elasmobranchii.” Quarterly Journal of Microscopical Science (1894–1895) 37: 87–101. Shadbolt, George. 1857. “The President’s Address for the Year 1857.” Quarterly Journal of Microscopical Science 5: 133–144. Siebold, Karl Theodor Ernst von. [1845–1848]. Anatomy of the Invertebrata (trans., Waldo I. Burnett), 2nd edn. Boston, 1874. Sloan, Phillip Reid. 1992. “Introductory Essay: On the Edge of Evolution.” In Richard Owen. The Hunterian Lectures in Comparative Anatomy, May–June 1837, ed. P. R. Sloan. London: Natural History Museum. Strick, James E. Forthcoming. Sparks of Life: Darwinism and the Victorian Spontaneous Generation Debates. Cambridge, MA: Harvard University Press. Thiselton-Dyer, W. T. 1925. “Plant Biology in the ‘Seventies.’ ” Nature (suppl. 9): 710. Tuchman, Arleen. 1993. Science, Medicine, and the State in Germany: The Case of Baden, 1816–1871. New York and Oxford: Oxford University Press. Tyson, James. 1870. The Cell Doctrine: Its History and Present State. Philadelphia: Lindsay & Blakiston. Vines, Sydney Howard. 1889. “An Examination of Some Points in Prof. Weismann’s Theory of Heredity.” Nature 40: 621–626. Wenham, F. H. 1856. “On the Formation and Development of the Vegetable Cell.” Quarterly Journal of Microscopical Science 4: 1–10. Whitman, Charles Otis. 1894. “The Inadequacy of the Cell-Theory of Development.” In Biological Lectures, Marine Biological Station, pp. 105–124. Boston: Ginn. Winsor, Mary P. 1976. Starfish, Jellyfish, and the Order of Life: Issues in Nineteenth-Century Science. New Haven: Yale University Press. Winter, Alison. 1997. “The Construction of Orthodoxies and Heterodoxies in the Early Victorian Life Sciences.” In Victorian Science in Context, ed. Bernard Lightman, pp. 24–50. Chicago: University of Chicago Press.