1907.] Wheeler, The Polymorphism of Ants. 65 



all the eggs which she lays, contains, of course, this germ-plasm which has 

 been modified by the autumnal regime and therefore presents all its modi- 

 fications. Now the conditions under which it is called upon to pursue its 

 development are not the same as those of the autumn, to which its germ- 

 plasm has been exclusively habituated during a very long series of genera- 

 tions. This germ-plasm whose fixed constitution is adapted to a precise 

 method of development in a given environment according to the queen 

 type, and has been determined by the conditions to which it has been sub- 

 jected for a great number of generations, finds itself in this particular egg 

 suddenly emancipated from these modifying conditions and subjected to 

 altogether new ones. What may we expect it to produce ? If the modifica- 

 tions to which it finds itself submitted are too severe, it must perish; if, on 

 the contrary, they are compatible with its evolution, it must proceed with 

 its development as well as it can, like an animal constrained to develop 

 under abnormal conditions. It is evident that the latter alternative alone 

 is to be considered, since the former would lead to the extinction of the 

 species. Now it is easy to see that this second alternative is nothing more 

 nor less than a case of experimental dichogeny." 



In a later paper Marchal ^ aptly designates the suppression of the func- 

 tional activity of the ovaries through the nursing, or nutricial habits of the 

 workers as nutricial castration. He has shown that by eliminating the 

 queen from the Vespa colony as many as a third of the workers become 

 fertile. A similar result is brought about by a suppression or merely by a 

 temporary suspension of the egg-laying of the queen. This can be due, 

 as he maintains, only to abolition of the nursing function and the appro- 

 priation by the workers of the food which under normal conditions they 

 would feed to the larvae. 



Marchal's view differs frorri that of Weismann in postulating a homo- 

 geneous germ-plasm and in rejecting representative units like the ids, 

 determinants, etc. He regards the "differentiation" of the queen as due 

 to the direct action of external conditions, especially of nourishment, and 

 the differentiation of the workers as belonging to a class of phenomena, 

 ^' which, if not essentially understood, are nevertheless known in their mani- 

 festations, namely teratogenesis and dichogeny." Although this view is 

 very similar to those of Spencer and Emery, the conception of nutricial 

 castration seems to me to represent a valuable addition and I shall revert 

 to it.2 



1 La Castration Nutricial chez les Hymenopterfes Sociaux. Compt. Rend. Sec. Biol., 5 

 Juin 1897, 2 pp. 



2 Nutricial castration (from nutrix, a nurse) must he (iistiiiKnistied from ' alimentary castra- 

 tion ' (Emery, Le Polymori)hisme, etc., Inr. cit.), altliouKh both are responsible for the infertility 

 of the worker. Through alimentary castration the development of the reproductive organs is 

 inhibited in the larva and pupa, and this inhibition is maintained in tlif adult by the strong 



[January, 1907] 6 



