Leibniz and his iatro-mechanics

In his philosophical writings, Leibniz regularly quotes Steno, Malpighi, Swammerdam and Leeuwenhock not only to defend the preformationistic hypothesis, but also to praise their scientific methods as exemplary: he emphasizes the accuracy of their observations, the usefulness of their analogies or their skill at finding some 'series' in natural transformations. We will first analyse some epistemological features of the scientific writings of these four naturalists, which both delineate their 'mechanism' and meet several Leibnizian postulates, namely transspecific analogy grounded on the uniformity of nature, anatomical resolution requiring a microscope to find the connection between phenomena, and finally the economy of postulates. Then, we will question the scientific implications of theoretical choices which are common to Leibniz's Protogaca and Steno's, Malpighi's and Swammerdam's writings about natural transformations. With this scientific background we can see how some mechanical assumptions shed light on Leibnizian conception of the continuity of thoughts.