Ute Deichmann

Avery’s et al. ’s 1944 paper provides the first direct evidence of DNA having gene-like properties and marks the beginning of a new phase in early molecular genetics (with a strong focus on chemistry and DNA). The study of its reception shows that on the whole, Avery’s results were immediately appreciated and motivated new research on transformation, the chemical nature of DNA’s biological specificity and bacteria genetics. It shows, too, that initial problems of transferring transformation to other systems and prominent criticism of its results nurtured skepticism. Avery’s experiment was downplayed and neglected particularly by many of those scientists who worked in the new fields of biochemical and biophysical genetics, genetic phage, and TMV research. This was not due to the fact that the implications of the paper could not be connected to generally accepted knowledge. Contrary to a widespread belief, the assumed uniformity of DNA as opposed to proteins was not used as an argument against the validity of Avery’s et al.’s finding. The indifference rather reflected, among other things, the disciplinary gap between the chemically oriented microbiologists and the old and new geneticists who remained committed to genetic and physical methods (in particular x-ray studies) and clung to the assumption that proteins were the sole carriers of biological specificity. The responses to Avery’s et al.’s paper show how different research interests in the areas between microbiology, genetics, and biochemistry interacted with the prejudices, dogmas, individual farsightedness or short-sightedness, and scientific authority during a pivotal period of early molecular biology.

Chemistry and biochemistry in Germany was notably affected by the dismissal and emigration of Jewish scientists. The expulsion of Jewish scientists aided to significantly reduce the international regard for German science, particularly in biochemistry, physical chemistry, and quantum chemistry, after 1945. In most cases remaining scientists adjusted quickly after 1933 to the new political circumstances, with a few exceptions. A number of them even actively supported the politics of National Socialism. This fact as well as the common stance to forget the 12 years of National Socialist rule complicated the exchange of international scientific knowledge after 1945 and delayed affiliation of the weakened fields of research to the level of international research.

Methods and equations for analysing the kinetics of enzyme-catalysed reactions were developed at the beginning of the 20th century in two centres in particular; in Paris, by Victor Henri, and, in Berlin, by Leonor Michaelis and Maud Menten. Henri made a detailed analysis of the work in this area that had preceded him, and arrived at a correct equation for the initial rate of reaction. However, his approach was open to the important objection that he took no account of the hydrogen-ion concentration (a subject largely undeveloped in his time). In addition, although he wrote down an expression for the initial rate of reaction and described the hyperbolic form of its dependence on the substrate concentration, he did not appreciate the great advantages that would come from analysis in terms of initial rates rather than time courses. Michaelis and Menten not only placed Henri's analysis on a firm experimental foundation, but also defined the experimental protocol that remains standard today. Here, we review this development, and discuss other scientific contributions of these individuals. The three parts have different authors, as indicated, and do not necessarily agree on all details, in particular about the relative importance of the contributions of Michaelis and Menten on the one hand and of Henri on the other. Rather than force the review into an unrealistic consensus, we consider it appropriate to leave the disagreements visible.

In contrast to anti-Jewish campaigns at German universities in the 19th century, which met with opposition from liberal scholars, among them prominent chemists, there was no public reaction to the dismissals in 1933. Germany had been an international leader in chemistry until the 1930s. Due to a high proportion of Jewish physicists, chemistry was strongly affected by the expulsion of scientists. Organic and inorganic chemistry were least affected, while biochemistry suffered most. Polymer chemistry and quantum chemistry, of minor importance among the majority of academic chemists was further weakened by the expulsion of renowned scientists. However, a look at the research carried out in Nazi Germany shows that no field of research "emigrated" as such, except research into molecular beams. The reception of emigré chemists differed with respect to their field of research and the degree of competition in the host countries. Thus biochemists and physical chemists were accepted at American universities, whereas organic chemists were not. In contrast, they received high positions in Turkey, Palestine/Israel, and Egypt. After WWII, few emigrés were asked to come back. The delay of the resumption of international contacts by German chemists contributed to the delay in rebuilding in particular German biochemistry, the physical chemistry of polymers, and physical organic chemistry.

Three early 20th-century attempts at unifying separate areas of biology, in particular development, genetics, physiology, and evolution, are compared in regard to their success and fruitfulness for further research: Jacques Loeb’s reductionist project of unifying approaches by physico-chemical explanations; Richard Goldschmidt’s anti-reductionist attempts to unify by integration; and Sewall Wright’s combination of reductionist research and vision of hierarchical genetic systems. Loeb’s program, demanding that all aspects of biology, including evolution, be studied by the methods of the experimental sciences, proved highly successful and indispensible for higher level investigations, even though evolutionary change and properties of biological systems up to now cannot be fully explained on the molecular level alone. Goldschmidt has been appraised as pioneer of physiological and developmental genetics and of a new evolutionary synthesis which transcended neo-Darwinism. However, this study concludes that his anti-reductionist attempts to integrate genetics, development and evolution have to be regarded as failures or dead ends. His grand speculations were based on the one hand on concepts and experimental systems that were too vague in order to stimulate further research, and on the other on experiments which in their core parts turned out not to be reproducible. In contrast, Sewall Wright, apart from being one of the architects of the neo-Darwinian synthesis of the 1930s, opened up new paths of testable quantitative developmental genetic investigations. He placed his research within a framework of logical reasoning, which resulted in the farsighted speculation that examinations of biological systems should be related to the regulation of hierarchical genetic subsystems, possibly providing a mechanism for development and evolution. I argue that his suggestion of basing the study of systems on clearly defined properties of the components has proved superior to Goldschmidt’s approach of studying systems as a whole, and that attempts to integrate different fields at a too early stage may prove futile or worse. © 2011 Elsevier Inc.

Dissatisfied with the descriptive and speculative methods of evolutionary biology of his time, the physiologist Jacques Loeb, best known for his “engineering” approach to biology, reflected on the possibilities of artificially creating life in the laboratory. With the objective of experimentally tackling one of the crucial questions of organic evolution, i.e., the origin of life from inanimate matter, he rejected claims made by contemporary scientists of having produced artificial life through osmotic growth processes in inorganic salt solutions. According to Loeb, the answer to the question of whether or not life could be created artificially had to come from macro-molecular chemistry, in particular from the research on the recently discovered DNA. He was convinced that a prerequisite for making living matter from inanimate substances was the chemical synthesis of nuclear material capable of self-replication. Moreover, Loeb, experimentally refuting some vitalistic explanations as well as colloidal chemists’ far-reaching claims that biologically relevant macromolecules follow colloidal rather than chemical laws, pioneered research on the physical and chemical explanations of biological phenomena.

For centuries the question of the origin of life had focused on the question of the spontaneous generation of life, at least primitive forms of life, from inanimate matter, an idea that had been promoted most prominently by Aristotle. The widespread belief in spontaneous generation, which had been adopted by the Church, too, was finally abandoned at the beginning of the twentieth century, when the question of the origin of life became related to that of the artificial generation of life in the laboratory. This paper examines the role of social authorities, researchers’ basic beliefs, crucial experiments, and scientific advance in the controversies about spontaneous generation from the seventeenth to the nineteenth centuries and analyzes the subsequent debates about the synthesis of artificial life in the changing scientific contexts of the nineteenth and early-twentieth centuries. It shows that despite the importance of social authorities, basic beliefs, and crucial experiments scientific advances, especially those in microbiology, were the single most important factor in the stepwise abandoning of the doctrine of spontaneous generation. Research on the origin of life and the artificial synthesis of life became scientifically addressed only when it got rid of the idea of constant smooth transitions between inanimate matter and life and explored possible chemical and physical mechanisms of the specificity of basic molecules and processes of life.