These, however, are not the only criticisms of the theory of mimicry which the study of this species forces upon us. _Papilio polytes_ is one of the few mimetic species that has been bred, and in no other case of polymorphism is the relation between the different forms so clearly understood. For this result we are indebted mainly to the careful experiments of Mr J. C. F. Fryer, who recently devoted the best part of two years to breeding the different forms of this butterfly in Ceylon[45]. Fryer came to the conclusion that an explanation of this curious case is possible on ordinary Mendelian lines. At first sight the breeding results appear complicated, for any one of the three forms of female can behave in several different ways. For the sake of simplicity we may for the moment class together the A and H females as the mimetic females, the non-mimetic being represented by the M or male-like females. {85} The different kinds of families which each of the three females can produce may be tabulated as follows:-- ([alpha]) The M form may give either:-- (1) M only. (2) M and mimetics in about equal numbers. (3) Mimetics only. ([beta]) The A form may give either:-- (1) M and mimetics in about equal numbers. (2) M and mimetics in the ratio of about 1:3. (3) Mimetics only. ([gamma]) The H form may give either:-- (1) M and mimetics in about equal numbers. (2) M and mimetics in the ratio of about 1:3. (3) Mimetics only. The males are in all cases alike to look at but it must nevertheless be supposed that they differ in their transmitting powers. In fact the evidence all points to there being three different kinds of male corresponding to the three different kinds of female. But they cannot shew any difference outwardly because there is always present in the male a factor which inhibits the production of the mimetic pattern even though the factor for that pattern be present. Returning now to the records of the females it will be noticed that although the M form may breed true the mimetics never give the M form alone. Where they give the M form among their progeny they produce mimetics and non-mimetics either in the ratio 1:1 or of 3:1. This at once suggests that the {86} non-mimetic is recessive to the mimetic forms--that the mimetics contain a factor which does not occur in the non-mimetics. If this factor, which may be called X, be added to the constitution of a non-mimetic female it turns it into a mimetic. If X be added to a male such an individual, though incapable of itself exhibiting the mimetic pattern owing to the inhibitory factor always present in that sex, becomes capable of transmitting the mimetic factor to its offspring. Expressed in the usual Mendelian way the formulae for these different butterflies are as follows:-- M[F] = iixx | Iixx = [M] (1) Mimetic } = { iiXX | IiXX = [M] (2) [F][F] } { or iiXx | IiXx = [M] (3)