Traversing birth: continuity and contingency in research on development in nineteenth-century life and human sciences.

In the history of life sciences, it has often been argued that the individual organism emerged, around 1800, as a four-dimensional entity--a temporalized entity. Against this backdrop, the article asks how research on development contributed to structuring the time of the organism in terms of a historical process, that is, by understanding a given phenomenon as brought forth by what preceded it and as establishing conditions for what will follow, thus relating the past, the present and the future in a specific way. To shed light on this conceptualization, we must take into account not only embryological research on morphogenesis but also physiological research on the genesis of vital functions and the causation of congenital anomalies. Three layers of structuring time in such research may be discerned: the making of a trans-natal continuity of the developing organism; a conceptualization of birth as a threshold of past and future that paradigmatically reveals the historical understanding of such developmental continuity; and an approach to intergenerational transmission that confronts developmental continuity with historical contingency. My contribution focuses on the work of William T. Preyer and Charles Féré but, in a genealogical vein, situates their work in the larger context of nineteenth-century research on development.