T. H. morgan as invertebrate embryologist

T. H. Morgan is known primarily for his work in genetics and for his "conversion" to the Mendelian-chromosome theory of inheritance in 1910. Standard accounts represent this conversion as evidence of Morgan's having seen the light of truth and progress in science and of his having cast off the shackles of his old embryological and morphological approach. In contrast, this paper suggests that the primary roots of Morgan's interest in heredity and development both lie in his work of the 1890s, and can be seen clearly in the work of 1895 at the Naples Zoological Station, where Morgan intensively studied isolated blastomeres of marine invertebrate eggs.