Marsha L. Richmond

T.H. Huxley's Criticism of German Cell Theory: An Epigenetic and Physiological Interpretation of Cell Structure

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 vonKölliker), 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.

The 1909 Darwin celebration: Reexamining evolution in the light of Mendel, mutation, and meiosis

In June 1909, scientists and dignitaries from 167 different countries gathered in Cambridge to celebrate the hundredth anniversary of Charles Darwin’s birth and the fiftieth anniversary of the publication of Origin of Species. The event was one of the most magnificent commemorations in the annals of science. Delegates gathered within the cloisters of Cambridge University not only to honor the “hero” of evolution but also to reassess the underpinnings of Darwinism at a critical juncture. With the mechanism of natural selection increasingly under attack, evolutionary theory was in disarray. Against this backdrop, biologists weighed the impact of several new developments—the rediscovery of Mendel’s laws of heredity, de Vriesian mutation theory, and the linkage of sex‐cell division (recently named “meiosis”) to the mechanism of heredity. The 1909 Darwin celebration thus represents a significant watershed in the history of modern biology that allows historians to assess the status of evolution prior to the advent of the chromosome theory of genetics.

Protozoa as Precursors of Metazoa: German Cell Theory and Its Critics at the Turn of the Century

ConclusionWith historical hindsight, it can be little questioned that the view of protozoa as unicellular organisms was important for the development of the discipline of protozoology. In the early years of this century, the assumption of unicellularity provided a sound justification for the study of protists: it linked them to the metazoa and supported the claim that the study of these “simple” unicellular organisms could shed light on the organization of the metazoan cell. This prospect was significant, given the state of cytology circa 1910. In the wake of the major gains made in understanding nuclear division in the last two decades of the nineteenth century, cytology was suddenly confronted with many, seemingly less penetrable, problems. Several aspects of nuclear organization still remained unexplained, and recent research had revealed the presence in the cytoplasm of structures whose functions in cell life were unknown. Classical methods of cytology, relying on descriptive, morphological analysis, seemed ill equipped to resolve these questions.Hertwigs program for protozoology, grounded in the assumption of the fundamental unity of organization in protozoa and metazoa, offered a potential means for investigating these and other problems of cell theory. Linked to mainstream cytology, protozoology was advocated as a means of experimentally investigating key biolobical processes — reproduction, metabolism, and organelle morphology and physiology — less accessible in higher organisms. Protozoa were hailed as prime experimental organisms, in which cell structure and function could be more easily studied. Unlike the metazoan cell, they could be subjected to controlled experiments in which the external environment was modified and the effects monitored. Protozoa offered, in other words, a promising experimental means by which to investigate the cell — its structures and its processes.The success of this program within Germany was soon apparent. In contrast to the rather neglected state of the discipline in 1900, protozoology began to be recognized as more than a somewhat obscure area of study for specialists. In practical terms, this translated into greater numbers of students attracted to the field, increased institutional support for the discipline, and its elevation in status within the biological sciences as new developments, particularly in connection with medical applications, began to draw attention to the field.64 The unicellular hypothesis also promoted the internal development of the science. It provided a rationale for introducing the various techniques used in cytology, embryology, physiology, and the new field of biochemistry as suitable research tools for protozoology as well. This vastly extended the research possibilities and facilitated the understanding of, among other things, protozoan organization, modes of reproduction, and evolutionary relationships. The new experimental grounding of the discipline in turn fitted in well with developments in biology at large: in contrast to the descriptive methodology that had predominated in the nineteenth century, this new experimental program placed protozoology at the forefront of the early twentieth-century movement to make biology an experimental science comparable to physics and chemistry.Yet the criticism of the unicellular hypothesis can also be seen as having served a valuable function within the development of the discipline. It focused attention on the study of protists as organisms in their own right, not simply as models for metazoan cells. More generally, it helped to remind biologists of the particular evolutionary assumptions that supported this conception. Dobell and other British critics pointed out, among other things, the association between the theory of recapitulation and the interpretation of protozoa as unicellular organisms. At the time when the recapitulation theory and the germ-layer doctrine were in decline, it was important to stress how these evolutionary ideas also entered into the contemporary concepts of subsidiary specialties. This was as true for protozoology as it was for cell theory itself. The chromidial theory, in its various guises, and the binuclearity hypothesis did in fact contain elements of recapitulationist reasoning, and they were open to criticism for the same kind of overly speculative theorizing that characterized this evolution theory. Dobells critique forced protozoologists and cell theorists alike to review the theoretical postulates guiding their investigations.In the absence of further historical studies, it is hard to evaluate the consequences of this debate in later years. The issue was not whether protozoa were the precursors of metazoa — both sides accepted this. They disagreed over which particular protozoon had served as the ancestral form, and this, in turn, influenced their stance on the question of unicellularity. The situation is little changed today. Because the former question is still an open one, the latter remains so too. Both of the models for the origin of multicellular organisms — colonies of ciliates versus multinucleate protists — are still presented as possible mechanisms in modern textbooks of evolution. Unable to judge the dispute in terms of the ultimate validity of the competing conceptions, the historian requires other criteria. It perhaps becomes more important to evaluate the issues in the context of the internal and external stimulus they provided the discipline.65 In these terms, and from the present historical vantage point, Hertwigs research program for protozoology, based upon the unicellular hypothesis, appears to have been a successful one.

A lab of one's own : The Balfour Biological Laboratory for Women at Cambridge University, 1884-1914

The Balfour Biological Laboratory for Women was established at Cambridge University in 1884 to prepare the students of Newnham and Girton Colleges to sit the Natural Sciences Tripos, first opened to women in 1881. For thirty years, until its closure in 1914, the Balfour Laboratory served as the central conduit for biological instruction for the women of Cambridge, introducing them to the new program of experimental biology developed by the physiologist Michael Foster and the embryologist Francis Maitland Balfour. Directed by distinguished women graduates, the Balfour Laboratory became recognized as the leading center for womens biological instruction in Britain. Its significance, however, extends beyond its nominal status as a teaching laboratory. It provided university positions for able scientists who otherwise would not have been placed, offered advanced students the opportunity to engage in independent research, and, most important, formed the locus for the scientific subculture created by women at Cambridge to compensate for their exclusion from the social community of science. Drawing upon college and university archival records, this essay offers institutional, social, and biographical research that broadens our understanding of the experience of the first generation of women to pursue a higher education in the life sciences at one of the worlds premier universities.

Opportunities for women in early genetics

Although women have long been engaged in science, their participation in large numbers was limited until they gained access to higher education in the last decades of the nineteenth century. The rediscovery of Mendels work in 1900 coincided with the availability of a well trained female scientific workforce, and women entered the new field in significant numbers. Exploring their activities reveals much about the early development of the field that soon revolutionized biology, and about the role of gender in the social organization of science.

British cell theory on the eve of genetics

Many historians have assumed that the advent of the chromosome theory of heredity and the theory of the gene settled the old debate over preformation versus epigenesis in favour of preformation. An analysis of the views of leading British cytologists between 1900 and 1920 indicates that the story is more complex. Cytologists could accept seemingly preformationist tenets about the hereditary factors and yet maintain an overall epigenetic view of organism development by assuming that genes interact dynamically with the cytoplasm and that the cell is influenced by its environment throughout growth and development.