This paper takes up some threads of Deleuze’s and Ruyer’s engagement with biology. I begin by laying out the main features of Deleuze’s scheme of morphogenesis, through the lens of his references to embryology. I take Deleuze’s interest in embryology to be guided by the effort to define bodies solely by form-generating factors which are immanent to them. His concept of virtuality, which indicates the creative component of reality, the open field of connections defining a body’s capacities for transformation and (...) interaction, plays a key role in this regard. I then consider two implications: (1) The insistence on morphogenesis displaces the question of life from given biological entities, which preserve themselves and act through regulated cycles, to the myriad of activities that compose and modify them; (2) It also rearticulates the distinction between the living and the nonliving, in that it separates the question of life from that of its emergence from a given material arrangement. In the second part I examine these points with greater reference to Ruyer. After introducing Ruyer’s concepts of functioning and formation, I focus on his account of the continuity between biological and physicochemical forms, following some of his work on the microbiology and ethology of the time. The real difference is not between the living and the nonliving, but between two modes of bonding and composition variously operating on all scales: morphogenetic and statistical. I conclude by assessing the significance of this claim with respect to the traditional distinction between vitalism and mechanism. (shrink)