 That is, we will have, if our research goes well, an account of what loss of leaves is. Along the way a process of identifying the kind, all and only the members of which will lose their leaves due to sap coagulation, is assumed. Yet the Analytics provides no systematic discussion about whether there are general criteria for identifying these basic scientific kinds. As we will see, this is the topic of one of the most interesting sections of On the Parts of Animals, book I.