The paper analyzes the early theory building process of Thomas Hunt Morgan from the 1910s to the 1930s and the introduction of the invisible gene as a main explanatory unit of heredity. Morgan’s work marks the transition between two different styles of thought. In the early 1900s, he shifted from an embryological study of the development of the organism to a study of the mechanism of genetic inheritance and gene action. According to his contemporaries as well as to historiography, Morgan (...) separated genetics from embryology, and the gene from the whole organism. Other scholars identified an underlying embryological focus in Morgan’s work throughout his career. Our paper aims to clarify the debate by concentrating on Morgan’s theory building—characterized by his confidence in the power of experimental methods, and carefully avoiding any ontological commitment towards the gene—and on the continuity of the questions to be addressed by both embryology and genetics. (shrink)

We outline three very different concepts of the gene—instrumental, nominal, and postgenomic. The instrumental gene has a critical role in the construction and interpretation of experiments in which the relationship between genotype and phenotype is explored via hybridization between organisms or directly between nucleic acid molecules. It also plays an important theoretical role in the foundations of disciplines such as quantitative genetics and population genetics. The nominal gene is a critical practical tool, allowing stable communication between bioscientists in a wide (...) range of fields grounded in well-defined sequences of nucleotides, but this concept does not embody major theoretical insights into genome structure or function. The post-genomic gene embodies the continuing project of understanding how genome structure supports genome function, but with a deflationary picture of the gene as a structural unit. This final concept of the gene poses a significant challenge to conventional assumptions about the relationship between genome structure and function, and between genotype and phenotype. (shrink)

This paper discusses some philosophical and historical connections between, and within, nineteenth century evolutionism and microscopical research. The principal actors are mainly Darwin, Schleiden, Whewell and the "London Doctors," Arthur Henfrey and Edwin Lankester. I demonstrate that the apparent alliances—particularly Darwin/Schleiden (through evolutionism) and Schleiden/Whewell (through Kantian philosophy of science)—obscure the deep methodological differences between evolutionist and microscopical biology that lingered on until the mid-twentieth century. Through an understanding of the little known significance of Schleiden's programme of microscopical research and (...) by comparing certain features of his methodology to the activities of the "London Doctors," we can identify the origin of this state of affairs. In addition, the outcome provides an insight into a critique of Buchdahl's view on Schleiden's philosophical conception. (shrink)