ORIGIN OF CASTES OF TERMITES 93 



Les larves au stade le plus jeune ont des organes genitaux extreme- 



ment reduits II est possible que, des cette periode de I'exist- 



ence des larves, il y ait deja lieu de distinguer deux categories d'individus 

 au point de vue du developpement des organes genitaux, ceux qui 

 doivent devenir sexues les ayant plus developpes. 



Again, in his study of the sex organs of the older stages there 

 is further evidence in favor of caste predetermination, but once 

 more Feytaud attributes these conditions to differences in regime. 

 He finds that in the second stage (2.25 to 3.75 mm.) the sex 

 organs are larger in the small headed, sexual, nymphs than in 

 the worker-soldier nymphs. The sex organs of both types are 

 now larger than in the first stage, which indicates that no arrest 

 of development has yet taken place in the worker-soldier gonads. 

 In stages III and IV (3.75 to 6 mm.) the sex organs of the sexual 

 nymphs increase greatly in size, and the cells are in the phases 

 of ovocytes and spermatocytes; on the other hand, the sex organs 

 of the worker-soldier nymphs have remained stationary, and 

 continue so into the adult stage, with the size found in stage II, 

 and the cells in the phases of ovogonia and spermatogonia. 

 Feytaud believes that the arrest of development is not final in 

 the worker-soldier type, but .that development may continue 

 when an individual has the same treatment as a sexual nymph : 



II est probable que I'arret de developpement des organes genitaux 

 n'est pas forcement definitif, et que ces organes conservent la' faculte 

 de poursuivre leur evolution, si, a une periode quelconque, I'individu 

 est soumis au meme regime que les larves de sexues. 



Feytaud notes that the nymphs of the second form have larger 

 and better developed sex organs than the nymphs of the first 

 form of similar age, and concludes that there is acceleration of 

 development in one case, retardation in the other, and that both 

 are due to differences in food and care. 



Les nymphes de 2me forme ont done des organes genitaux beaucoup 

 mieux developpes que les nymphes de Ire forme du meme age. 



"Les deux categories de nymphes proviennent de larves qui, au 

 Ire age, etaient identiques. II s'est done produit une acceleration de 

 developpement dans un cas, un retard dans I'autre. Cette difference 

 d'evolution est certainement sous la dependence d'une difference de 

 regime. 



