XI] CONCLUSION 141 



the intermediate steps do not reappear? Why is it 

 that when the altered germplasm is mingled with the 

 original germplasm the various postulated stages be- 

 tween them are not reformed ? For in various cases 

 where we know the course of evolution this does occur. 

 The pale pink sweet-pea has come from the wild purple 

 by a series of definite steps, and when it is crossed back 

 with the wild form the resulting plants give the series 

 of stages that have occurred in the evolution of the 

 pink. So also when the orange rabbit is crossed with 

 the wild grey form and the offspring are inbred there 

 are reproduced the black, the tortoisesheU, and the 

 chocolate, forms which are stages in the evolution of 

 the orange from the wild grey. If then, to take an 

 example, the "aristolochiae" form of Papilio polytes 

 has been derived from the male-like form by a series 

 of steps, why do we not get these steps reproduced 

 after the germplasms of the two forms have been 

 mingled? From the standpoint of modern genetic 

 work the inference is that these postulated inter- 

 mediate steps have never existed — that the one form 

 of polytes female came directly from the other, and 

 was not built up gradually through a series of stages 

 by the selective agency of birds or any other dis- 

 criminating enemy. 



These two objections, viz. the difficulty of finding 

 the appropriate enemy, and the non-appearance of 

 intermediates when the extreme forms are crossed, 

 may, perhaps, be said to constitute the main objections 

 to the current theory of mimicry. Others such as 



