152 Appendix. 



to the cold, the most decided changes having been 

 effected in them. 



The resulting butterflies were all of one form, although 

 both might have been expected to appear under natural 

 circumstances. 



Dr. Weismann's remarks on the foregoing experiments. 

 The author of the present work has, at my request, 

 been good enough to furnish the following remarks upon 

 Mr. Edward's experiments with G. Interrogations : 



The interesting experiments of Mr. Edwards are here 

 principally introduced because they show how many 

 weighty questions in connexion with seasonal dimorphism 

 still remain to be solved. The present experiments do 

 not offer a direct but, at most, only an indirect proof of the 

 truth of my theory, since they show that the explanation 

 opposed to mine is also in this case inadmissible. Thus 

 we have here, as with Papilio Ajax, two out of the four 

 annual generations mixed, i.e., consisting of summer and 

 winter forms, and the conclusion is inevitable that these 

 forms were not produced by the gradual action of heat 

 or cold. When, from pupae of the same generation 

 which are developed under precisely the same external 

 conditions, both forms of the butterfly are produced, the 

 cause of their diversity cannot lie in these conditions. 

 It must rather depend on causes innate in the organism 

 itself, i.e., on inherited duplicating tendencies which 

 meet in the same generation, and to a certain extent 

 contend with each other for precedence. The two forms 

 must have had their origin in earlier generations, and 

 there is nothing against the view that they have arisen 

 through the gradual augmentation of the influences of 

 temperature. 



In another sense, however, one might perceive, in the 

 facts discovered by Edwards, an objection to my theory. 



By the action of cold the form Umbrosa, which flies in 

 June, was produced. Now we should be inclined to 



