GENITAL ORGANS OF THE MALE. 



627 



monly found in semen after the age of seventy or seventy-five 

 years is past. The spermatozoa of different animals vary in size, 

 though their general appearance is much the same (Fig. 405). 



Their number is very great ; some writers state that in a single 

 ejaculation as many as 25,000,000 may be discharged, while one 

 has placed their number as high as 412,500,000. Both figures may 

 be correct, inasmuch as the amount of semen ejaculated varies at 

 each emission. 



The seminiferous tubules terminate at the apices of the lobules 



FIG. 407. Vas deferens 

 and seminal vesicle, A, seen 

 in longitudinal and, B, in 

 horizontal section : 1, vas 

 deferens; 2, its terminal or 

 ampullary portion; 3, semi- 

 nal vesicle with, 3', its 

 partitions; 4, its terminal 

 portion ; 5, ejaculatory duct 

 (Testut). 



FIG. 408. Eight seminal vesicle, unfolded and 

 seen on its posterior aspect (subject of forty years, 

 previous injection of tallow) : 1, vas deferens, with, 

 1', its ampulla ; 2, seminal vesicle with, 3, its lateral 

 prolongation ; 4, its enlargements in form of cecum ; 

 5, protuberances of its wall ; 6, junction of the 

 vesicle and vas deferens ; 7, ejaculatory duct 

 (the dotted line, x x, indicates the level of the 

 upper extremity of the vesicle before its unfolding) 

 (Testut). 



in the vasa recta (straight tubes), about thirty in number. In the 

 mediastinum these tubes form a network, the rete testis, the 

 vessels of which end in the vasa efferentia, about fifteen in number. 

 These vessels connect the testicles, with the epididymis, the con- 

 tinuation of which is the vas deferens. The canals of the rete 

 testis are lined by non-ciliated epithelium ; the vas aberrans, how- 



