7 86 EMBRYOLOGY 



In old men the seminal vesicles may not contain spermatozoids ; but 

 this is not always the case, even in very advanced life. Instances are 

 constantly occurring of men who have children in their old age, in 

 which the paternity of the offspring can hardly be doubted. Duplay, 

 in 1852, examined the semen of a number of old men, and found, in 

 about half the number, spermatozoids, normal in appearance and num- 

 ber, though in some the vesiculae seminales contained either none or 

 very few. Some of the persons in whom the spermatozoids were nor- 

 mal were between seventy-three and eighty-two years of age. These 

 observations were confirmed by Dieu, who found spermatozoids in a 

 man eighty-six years of age. The contents of the seminal vesicles, in 

 these cases, were examined twenty-four hours after death. Some of 

 the subjects died of acute, and others, of chronic diseases ; but the mode 

 of death did not present any differences in the cases classed with refer- 

 ence to the presence of spermatozoids. As the result of his own and 

 of other recorded observations, Dieu concluded that the power of fecun- 

 dation often persists for a considerable time after copulation has become 

 impossible on account simply of loss of the power of erection. 



