At the beginning of the twentieth century, several promising young American biologists – people such as E. B. Wilson, T. H. Morgan, E. G. Conklin, R. G. Harrison, F. R. Lillie, E. E. Just and, of course, Ritter and Child – endorsed diverse forms of organicism. In one of the most successful late nineteenth-century American textbooks, E. B. Wilson pointed out that ‘as far as the plants are concerned … it has conclusively been shown by Hofmeister, De Bary and Sachs that the growth of the mass is the primary factor; for the characteristic mode of growth is often shown by the growing mass before it splits up into cells, and the form of cell-division adapts itself to that of the mass: “die Pflanze bildet Zellen, nicht die Zelle bildet Pflanzen” (De Bary)’. Paralleling Whitman, Wilson concluded: ‘Much of the recent work in normal and experimental embryology, as well as that of regeneration, indicates that the same is true in principle of animal growth’. Many of these young investigators endorsed what their teachers taught them: people such as H. N. Martin and W. K. Brooks at Johns Hopkins, and former Leuckart students such as C. Whitman at the University of Chicago and C. Minot and E. Mark at Harvard. As a result, during the very first decades of the twentieth century, what I have defined as Romantic tradition thrived in many leading American departments of zoology.

We have already seen that part of the reason why such a tradition spread in the United States was that many American biologists spent a significant part of their training in Europe, and especially in Germany. Then, after their stay abroad, they were able to get a job in the US and make careers in important institutions – institutions they helped to shape according to the philosophies and experimental practices acquired in the Old World.