MALE ELEMENTS OF GENERATION. 789 



The ejaculatory ducts are formed by the union of the vasa deferentia with 

 the ducts of the vesiculae seminales on either side, and they open into the 

 prostatic portion of the urethra. Except that their coats are much thinner, 

 they have essentially the same structure as the vasa deferentia. 



Prostate. Surrounding the vesical extremity of the urethra, including 

 what is known as its prostatic portion, is the prostate gland, or body. This 

 organ, except as it secretes a fluid which forms a part of the ejaculated semen, 

 has chiefly a surgical interest, so that it is unnecessary to describe minutely 

 its form and relations. It is enveloped in a very dense, fibrous coat, contains 

 many glandular structures opening into the urethra, and presents a great num- 

 ber of non-striated, with a few striated muscular fibres, some just beneath the 

 fibrous coat and others penetrating its substance and surrounding the glands. 



The glands of the prostate are most distinct at that portion which lies 

 behind the urethra. In the posterior portion of this canal are found about 

 twenty openings, which lead to tubes ramifying in the glandular substance. 

 These tubes are formed of a structureless membrane branching as it pene- 

 trates the gland. They present hemispherical diverticula in their course, and 

 terminate in dilated extremities, which are looped and coiled. In the deeper 

 portions of the tubes, the epithelium is columnar or cubical, becoming tessel- 

 lated near their openings, and sometimes laminated. 



The prostatic fluid probably is secreted only at the moment of ejaculation. 

 Its characters will be considered in connection with the composition of the 

 seminal fluid. According to Kraus the prostatic fluid has an important 

 office in maintaining the vitality of the spermatozoids. " The spermatozoa, 

 in the absence of the prostatic fluid, can not live in the mucous membrane of 

 the uterus of mammalia ; but with its aid they may live for a long time in 

 the uterine mucus, often more than thirty-six hours." 



Glands of the Urethra. In front of the prostate, opening into the bulb- 

 ous portion of the urethra, are two small, racemose glands, called the glands 

 of Mery or of Cowper. These have each a single excretory duct, are lined 

 throughout with cylindrical epithelium, and secrete a viscid, mucus-like fluid, 

 which forms a part of the ejaculated semen. Sometimes there exists only a 

 single gland, and occasionally, though rarely, both are absent. Their uses 

 are probably not very important. 



The glands of Littre, found throughout the entire urethra and most 

 abundant on its anterior surface, are simple racemose glands, extending be- 

 neath the mucous membrane into the muscular structure, presenting here 

 four or five acini. As these acini are surrounded by muscular fibres, it is 

 easy to understand how their secretion may be pressed out during erection of 

 the penis. They are lined throughout with columnar or conoidal epithelium, 

 and secrete a clear and somewhat viscid mucus, which is mixed with the 

 ejaculated semen. 



MALE ELEMENTS OF GENERATION. 



The spermatozoids are the essential, male elements of generation, and 

 these are produced in the substance of the testicle, by a process analogous to 



