Recent studies have shown that Hugo de Vries did not rediscover Mendel's laws independently and that the classical story of the rediscovery of Mendel is largely a myth. Until now, however, no satisfactory account has been provided of the background and development of de Vries' views on heredity and evolution. The basic tenets of de Vries' Mutationstheorie and his conception of Mendelism are still insufficiently understood. It has been suggested that de Vries failed to assimilate Mendelism and that he wrote (...) his Mutationstheorie in a state of confusion. In this paper I argue that we can arrive at a better understanding by adopting a more symmetrical approach. My analysis will concentrate on three important aspects of de Vries' thinking which have been insufficiently appreciated until now. The first is that de Vries' reading of Mendel compelled him to change his conception of the hereditary particles, the pangenes, in a fundamental way. The second is de Vries' use of the notion of ‘hereditary force’. The third revolves around de Vries' typological species concept, which has been the source of much confusion in the literature. I shall conclude that de Vries did succeed in incorporating ‘Mendelism’ into his wider views on heredity and evolution, and that he did manage to handle his evidence in a consistent way. Yet I shall also conclude that Mendelism, in de Vries' interpretation, had nothing to do with ‘normal’ heredity and was mainly a laboratory phenomenon. (shrink)

In the 1940s and 1950s, Dutch scientists became increasingly critical of the practices of commercial dairy cattle breeders. Milk yields had hardly increased for decades, and the scientists believed this to be due to the fact that breeders still judged the hereditary potential of their animals on the basis of outward characteristics. An objective verdict on the qualities of breeding stock could only be obtained by progeny testing, the scientists contended: the best animals were those that produced the most productive (...) offspring. Some scientists had been making this claim since the beginning of the twentieth century. Why was it that their advice was apparently not heeded by breeders for so long? And what were the methods and beliefs that guided their practices? In this paper I intend to answer these questions by analysing the practical realities of dairy farming and stock breeding in The Netherlands between 1900 and 1950. Breeders continued to employ traditional breeding methods that had proven their effectiveness since the late eighteenth century. Their methods consisted in inbreeding - breeding in 'bloodlines,' as they called it - and selection on the basis of pedigree, conformation and milk recording data. Their aims were 'purity' and 'uniformity' of type. Progeny testing was not practiced due to practical difficulties. Before World War II, scientists acknowledged that genetic theory was of little practical use to breeders of livestock. Still, hereditary theory was considered to be helpful to assess the value of the breeders' methods. For instance, striving for purity was deemed to be consistent with Mendelian theory. Yet the term purity had different connotations for scientists and practical workers. For the former, it referred to homozygosity; for the latter, it rather buttressed the constancy of a distinct commercial ' brand.' Until the 1940s, practical breeders and most scientists were agreed that selecting animals purely for production was ill-advised. Cows of the extreme dairy type were believed to be prone to bovine tuberculosis. This conviction was at the basis of the development of 'the modern Friesian,' a rather robust type of dairy cow that was also valued for its aesthetically pleasing conformation and that became a commercial success. Contrary to the scientists' claims, it was not only for commercial reasons that breeders were reluctant to give up their modern Friesians after World War II, when the introduction of artificial insemination opened up the possibility of breeding more productive types by means of progeny testing. The political economy of breeding did indeed require breeders to protect their breed as a recognisable brand. Yet the moral economy of breeding must also be taken into account: the modern Friesian was also a product of widely shared normative standards of good and responsible farming. (shrink)

In the 1940s and 1950s, Dutch scientists became increasingly critical of the practices of commercial dairy cattle breeders. Milk yields had hardly increased for decades, and the scientists believed this to be due to the fact that breeders still judged the hereditary potential of their animals on the basis of outward characteristics. An objective verdict on the qualities of breeding stock could only be obtained by progeny testing, the scientists contended: the best animals were those that produced the most productive (...) offspring. Some scientists had been making this claim since the beginning of the twentieth century. Why was it that their advice was apparently not heeded by breeders for so long? And what were the methods and beliefs that guided their practices? In this paper I intend to answer these questions by analysing the practical realities of dairy farming and stock breeding in The Netherlands between 1900 and 1950. Breeders continued to employ traditional breeding methods that had proven their effectiveness since the late eighteenth century. Their methods consisted in inbreeding - breeding in 'bloodlines,' as they called it - and selection on the basis of pedigree, conformation and milk recording data. Their aims were 'purity' and 'uniformity' of type. Progeny testing was not practiced due to practical difficulties. Before World War II, scientists acknowledged that genetic theory was of little practical use to breeders of livestock. Still, hereditary theory was considered to be helpful to assess the value of the breeders' methods. For instance, striving for purity was deemed to be consistent with Mendelian theory. Yet the term purity had different connotations for scientists and practical workers. For the former, it referred to homozygosity; for the latter, it rather buttressed the constancy of a distinct commercial ' brand.' Until the 1940s, practical breeders and most scientists were agreed that selecting animals purely for production was ill-advised. Cows of the extreme dairy type were believed to be prone to bovine tuberculosis. This conviction was at the basis of the development of 'the modern Friesian,' a rather robust type of dairy cow that was also valued for its aesthetically pleasing conformation and that became a commercial success. Contrary to the scientists' claims, it was not only for commercial reasons that breeders were reluctant to give up their modern Friesians after World War II, when the introduction of artificial insemination opened up the possibility of breeding more productive types by means of progeny testing. The political economy of breeding did indeed require breeders to protect their breed as a recognisable brand. Yet the moral economy of breeding must also be taken into account: the modern Friesian was also a product of widely shared normative standards of good and responsible farming. (shrink)

The analogy between artificial selection of domestic varieties and natural selection in nature was a vital element of Darwin's argument in his Origin of Species. Ever since, the image of breeders creating new varieties by artificial selection has served as a convincing illustration of how the theory works. In this paper I argue that we need to reconsider our understanding of Darwin's analogy. Contrary to what is often assumed, nineteenth-century animal breeding practices constituted a highly controversial field that was fraught (...) with difficulties. It was only with considerable effort that Darwin forged his analogy, and he only succeeded by downplaying the importance of two other breeding techniques - crossing of varieties and inbreeding - that many breeders deemed essential to obtain new varieties. Part of the explanation for Darwin's gloss on breeding practices, I shall argue, was that the methods of his main informants, the breeders of fancy pigeons, were not representative of what went on in the breeding world at large. Darwin seems to have been eager to take the pigeon fanciers at their word, however, as it was only their methods that provided him with the perfect analogy with natural selection. Thus while his studies of domestic varieties were important for the development of the concept of natural selection, the reverse was also true: Darwin's comprehension of breeding practices was moulded by his understanding of the working of natural selection in nature. Historical studies of domestic breeding practices in the eighteenth and nineteenth century confirm that, besides selection, the techniques of inbreeding and crossing were much more important than Darwin's interpretation allowed for. And they still are today. This calls for a reconsideration of the pedagogic use of Darwin's analogy too. (shrink)

Historians of science have repeatedly, and justly, pointed to the discrepancy between theory and practice in the writings of Cuvier. This discrepancy is especially conspicious in his palaeontological works. No satisfactory analysis of the relation between theory and practice in Cuvier's palaeontology has appeared as yet. In this paper I shall point out the shortcomings of the interpretations of E. S. Russell, H. Daudin, W. Coleman, M. J. S. Rudwick and B. Balan. These authors either overrated or underestimated the role (...) Cuvier's anatomical rules played in his research. Next I shall argue that theory, as embodied in the anatomical rules, played an important role in Cuvier's study of fossil animals. However, the rules were not used as abstract principles of reconstruction. It is a persistent misconception that Cuvier's main concern in the Recherches sur les ossemens fossiles was the reconstruction of extinct animals. Most memoirs deal only with the identification, description and classification of fossil remains. It was mainly on this level that Cuvier—successfully—applied the anatomical rules. As an example of the use he made of the rules, Cuvier's study of the fossil mosasaur from Masstricht will be discussed. This example will also provide a clue to an alternative explanation of the discrepancy between theory and practice in the Recherches. I shall argue that Cuvier's theoretical claims must in part be qualified as examples of his great talent for image-building. (shrink)