The only other experiments comparable with these on _P. polytes_ are some made by Jacobsen on _Papilio memnon_ in Java[46]. Here again there are three forms of female, one of which, _laomedon_, is something like the male, while the other two, _agenor_ and _achates_, are quite distinct. Of these three _achates_, unlike the male and the other two females, is tailed, and resembles {90} the species _Papilio coon_ which belongs to the same presumably distasteful group as _P. aristolochiae_. These experiments of Jacobsen's are not so complete as the series on _P. polytes_, but Professor de Meijere and Mr Fryer have both pointed out that they are capable of being interpreted on the same simple lines. Another instance of experimental breeding involving polymorphism and mimicry in the female sex is that of the African _Papilio dardanus_, but the case is here complicated by the greater number of female forms (cf. pp. 30-33). The data, too, are far more scanty than in the other two cases, but so far as they go there is nothing to preclude an explanation being eventually arrived at on similar lines[47]. And now we may consider briefly the bearing of these experiments on the theory of mimicry. Throughout the work no individuals intermediate between the three well-marked forms of _polytes_ were met with. There is no difference in appearance between the heterozygous and the homozygous mimetic insects, whether they belong to the A or to the H form. The factor X, whether inherited from both parents, or from one only, produces its full effect, and the same is also true of the action of the factor Y. Now the most generally accepted hypothesis as to the formation of these mimetic resemblances supposes that they have been brought about through the gradual operation of natural selection accumulating slight variations. {91} Professor Poulton, for example, a prominent exponent of this school, considers that the A form of female was first evolved gradually from the M form, and later on the H form came by degrees from the A form. If this be true we ought, by mingling the M germ plasm with the H germ plasm and by subsequently breeding from the insects produced, to get back our series of hypothetical intermediates, or at any rate some of them. We ought as it were to reverse the process by which the evolution of the different forms has taken place. But as is shewn by the experiment of Mr Fryer, which was quoted above, nothing of the sort happens.