The proof that mimetic forms actually mimic their models is accepted. The discussion largely revolves around its manifestations in Lepidoptera. Sex-controlled polymorphism, parallel behavior of sexual dimorphism, mimicry rings, variability of mimics, genetics and origin of mimicry are topics discussed. The bearing of Mendelian inheritance upon the evolution of mimetic form is, in the author''s opinion, quite different than the pioneers of Mendelism took it to be, for nowhere has the current of opinion introduced such discrepancies as in the interpretation of such resemblances. The difficulty of neo-Darwinians to an origin in a single step is probably based oh their conviction that all cases of evolution must be explained by the selection of small deviations. Fisher''s theory of evolution of dominance by selection of modifiers is not unassailable in principle in all cases. There must have been present at the time of the "switch" or controlling gene for polymorphism, a series of modifiers capable of changing the effect of that mutant, and some of the modifiers were acting in a direction which, by chance, improved the mimetic resemblance.