CASTES OF TERMOPSIS 523 



slender (fig. 22), several small lobes merging into one larger lobe, 

 and finally all uniting at the base of the testis into one common 

 space, with which the vas deferens is connected. The vasa de- 

 ferentia are attenuated lobes with thin walls, the same is true of 

 the small and poorly developed tubules of the vestigial sem- 

 inal vesicles. The paired character of the seminal vesicles is 

 especially well seen in the soldier. 



Sections of the testes of the adult soldier show that there is a 

 complete breaking down of the inner ends of the lobes into a 

 central chamber or space, so that the base of the testis makes one 

 big sac with slender shrunken lobes leading to it, the remaining 

 spermatogonia and spermatocytes occupying a few cysts at the 

 tips of the lobes. In some adults the central space is filled by 

 masses of developing or possibly degenerating spermatids inter- 

 spersed with a few spermatozoa. In other, older, individuals the 

 spermatozoa predominate over the spermatids. A very few swol- 

 len spermatids and some spermatozoa were noted in the vas 

 deferens of one adult soldier. No spermatozoa were found in 

 the seminal vesicles. The slender tubules of the seminal vesicles 

 of the adult soldier, as seen in sections, consist of an outer layer 

 of slender epithelial cells less than one-half as tall as the similar 

 cells of the reproductive castes, and lacking the dark staining 

 secretion granules that are so abundant in the latter. Only a 

 very small amount of yellow staining secretion (iron haematoxy- 

 hn and orange G) is found in the lumen of the seminal vesicle 

 tubules of the soldier, in contrast to the copious secretion of the 

 reproductive forms. 



From the facts just stated, it seems evident that, although 

 the testes of the adult soldier produce spermatozoa that are ap- 

 parently normal, the lack of the secretion of the seminal vesicles 

 may render these spermatozoa non-functional and thus cause the 

 sterihty of the male soldier. A detailed cytological study of the 

 soldier spermatozoa may prove that they lack some morphological 

 feature or that they are entirely normal, but the attenuated vasa 

 deferentia and the degenerate seminal vesicles indicate that these 

 parts at least of the male reproductive sj^stem are vestigial. 

 An examination of the gonads of the j^oung male soldier with 



