STRUCTURE OF THE TESTES AND SPERMATOZOA. 



439 



In the small less defined testicular vesicles one finds, moreover, 

 simple nucleated cells, which by growth and endogenous multiplica- 

 tion produce the above-mentioned elements. 



FIG. 249. Generative organs of Tcenia saginata ( x 10.) Male organs. 

 t., testes ; v.d., vas deferens ; c.p., cirrhus-pouch. Female organs. ov., 

 ovary ; y.g., yolk-gland ; m.b., shell-gland (Mehlis' body) ; r.s., receptaculum 

 seminis; ut., uterus; v., vagina; g.p., genital papilla ; cl. y cloaca. 



The testes, when full of ripe spermatozoa, have their original 

 spherical form modified, inasmuch as they are each drawn out at one 

 point into a pointed process, by means of which they are fixed like 

 berries to the ramifications of the vas deferens. The latter is quite 

 conspicuous as in other Cestodes, and its course across the joint from 

 the porus genitalis to the uterus can be followed even with the naked 

 eye, but the processes are, on the contrary, seldom seen with great 

 definiteness. To the older anatomists both they and the testes were 

 alike unknown, and, till F. S. Schultze's discovery, the latter were 

 very generally identified with the vas deferens. 



In favourable specimens we can observe that these processes pro- 

 ceed wholly from the posterior end of the vas deferens. This is seen 

 (Fig. 249) to be continued into a number of thin canals which run in 

 an almost radiate manner from the point of origin, and break up into 

 finer twigs. The majority of these canals belong, of course, to the 

 anterior half of the joint, but some also run backwards. Here and 

 there they become almost varicose by the accumulation of spermatic 

 elements within them. This can be occasionally seen even in the 

 ripe proglottides where the testes have long since degenerated, and 



