Vital forces and epigenesis

If the irreducibility of vital properties is a condition for the concept of organism, then a third condition of the concept of organism is the idea of a vital force. For German natural philosophers at the time of Kant, this notion emerged during discussions on epigenesis, and particularly through the work of Caspar Wolff, who introduced it into German science at the end of the century. But to grasp the significance of Wolff’s Theoria generationis (1758; German version Theorie der Generation, 1764) for our purposes, we need to go back in time a little. In 1741, Swiss naturalist Abraham Trembley conducted the curious experiment described in his Mémoire pour servir à l’histoire d’un genre de polype d’eau douce, à bras en forme de cornes (1744), of an animal reproducing in the manner of plants (the youngling is formed from the body of the adult). Above all, the polyp is constituted in such a way that, when cut in two halves, two analogous animals are created, which are endowed with the same strange property of identical preservation. ¹ As Roger (1963, p.395) pointed out, this demonstrates “the polyp’s power of regeneration”; ² noticeably, it is no longer the regeneration of a leg or limb, but of the entire animal. This seems to be where the explanatory power of the mechanistic model ends: no machine can repair itself and also multiply itself after sectioning. Trembley’s experiment suggested a power inherent in living matter that goes beyond the powers of mechanical arrangement alone.