However, in recent years more and more indications have come up (from strictly theoretical, and from strictly physical, and finally also from paleontological considerations), pointing to an abrupt or jumpy organic evolution, in which we in fact have to do with dissipative dynamical systems (that is, organisms, more precisely : epigenetic sequences, see the document Non-living Dissipative Systems (First Series of Documents) in First Part of Website ) switching discontinuously from the one dynamic (and therefore morphological) regime, via an unstable phase, to another (relatively stable) dynamic regime. So instead of with quasi continuous change, we have to do with discontinuous change of the whatness of an (initial) organism. However, we should realize that the mentioned dissipative structures are no more than certain physical models for organisms. What precisely organisms are, also these models cannot tell.
And even if the transitions between beings were continuous as regards content, one still can theoretically assess the differences between two consecutive beings, in the same way as one has done it with the phases of continuous motion which continuously follow up upon each other. One thereby switches over from difference quotients to differential quotients. These latter involve infinitesimal ( = infinitely small) differences. Mutatis mutandis things could be like this in the case of differentiae of definitions.