This paper considers the foundational role of the contagium vivum fluidum—first proposed by the Dutch microbiologist Martinus Beijerinck in 1898—in the history of virology, particularly in shaping the modern virus concept, defined in the 1950s. Investigating the cause of mosaic disease of tobacco, previously shown to be an invisible and filterable entity, Beijerinck concluded that it was neither particulate like the bacteria implicated in certain infectious diseases, nor soluble like the toxins and enzymes responsible for symptoms in others. He offered (...) a completely new explanation, proposing that the agent was a “living infectious fluid” whose reproduction was intimately linked to that of its host cell. Difficult to test at the time, the contagium vivum fluidum languished in obscurity for more than three decades. Subsequent advances in technologies prompted virus researchers of the 1930s and 1940s—the first to separate themselves from bacteriologists—to revive the idea. They found in it both the seeds for their emerging virus concept and a way to bring hitherto opposing thought styles about the nature of viruses and life together in consensus. Thus, they resurrected Beijerinck as the founding father, and contagium vivum fluidum as the core concept of their discipline. (shrink)

Recent reinterpretations of Mendel's 1865 paper on Pisum as normal nineteenth-century science do not automatically solve the neglect issue. Those who argue that there were cognitive grounds for its neglect have only created a greater paradox, for if Mendel's work was not ahead of its time but was simply excellent normal science, then it should have been used by his contemporaries, as indeed was his work on Hieracium, which was average work. An examination of the nineteenth-century data in terms of (...) recent knowledge about scientific communication suggests that knowledge of Mendel's Pisum work never entered the informal communication network of nineteenth-century botany, and that very few individuals, either by chance or referral, located the Brünn Verhandlungen and read the paper. By this interpretation, Mendel's work was not neglected, it was not known. (shrink)

Textbook descriptions of the foundations of Genetics give the impression that besides Mendel’s no other research on heredity took place during the nineteenth century. However, the publication of the Origin of Species in 1859, and the criticism that it received, placed the study of heredity at the centre of biological thought. Consequently, Herbert Spencer, Charles Darwin himself, Francis Galton, William Keith Brooks, Carl von Nägeli, August Weismann, and Hugo de Vries attempted to develop theories of heredity under an evolutionary perspective, (...) and they were all influenced by each other in various ways. Nonetheless, only Nägeli became aware of Mendel’s experimental work; it has also been questioned whether Mendel even had the intention to develop a theory of heredity. In this article, a short presentation of these theories is made, based on the original writings. The major aim of this article is to suggest that Mendel was definitely not the only one studying heredity before 1900, if he even did this, as may be inferred by textbooks. Although his work had a major impact after 1900, it had no impact during the latter half of the nineteenth century when an active community of students of heredity emerged. Thus, textbooks should not only present the work of Mendel, but also provide a wider view of the actual history and a depiction of science as a social process. (shrink)