XII] THE M.AXrE GENERATIVE ORGANS 155 



He .suggests that there is a relation between the size of the am- 

 pulla and the time occujned by coition, stating that in dogs, cats 

 and boars where coition is a slow process the ampulla is small or 

 absent, Avhereas in horses and sheep where coition occupies a 

 relatively short time the amjiulla is well develoi^ed. 



The vesicvlae seminahs are situated at the ends of the vasa 

 deferentia. They are provided with a glandular epithelium, out- 

 side of which are thin muscular layers. It was formerly supposed 

 that they were of the nature of seminal reservoirs, but even in the 

 hedgehog, in which these organs undergo a very great develop- 

 ment at the breeding season, it has been impossible to find sperma- 

 tozoa in the vesicular fluid. On the other hand they contain a 

 large quantity- of glairy, milky fluid with much crystalloid 

 material, ^hich Ho^jkins has shown to consist of a phospho- 

 protein. The precise function of the vesiculae must stiU be re- 

 garded as undecided. It would seem probable that one of their 

 functions is to dilute the semen and so assist in providing a 

 medium for the transference of the spermatozoa. 



The ■prostate is a tubular gland surrounding the urethra at the 

 base of the bladder. It communicates Avith the vuethra by nume- 

 rous small ducts. Associated with the glandular tissue are a 

 ninuber of smooth muscle fibres, and there is an abundance of 

 vessels supplying the gland. The prostatic secretion is viscid. It 

 contains proteins and salts, and is sometimes very slightly acid 

 in reaction. In old subjects concretions are frequentl}^ present in 

 the gland. Concerning the function of the prostatic fluid nothing 

 definite is known. It has been suggested that it assists in providing 

 the spermatozoa Avith nutriment, and it is obvious that it con- 

 tributes additional fluid to the semen. It is not improbable that 

 one of its main functions is to cleanse the urethra of urine prior 

 to the ejaculation of spermatozoa, for it has been ascertained that 

 in a normal seminal ejaculation in the horse the first fluid to be 

 discharged contains no sperms and is almost certainly chiefly 

 of prostatic origin. 



Cowper's glands are a pair of small tubulo-racemose glands 

 situated near the anterior end of the urethra with Avhich they 

 communicate by two ducts. The glands are lined internally by a 

 secretory epithelium. The significance of the viscous secretion 

 which the glands produce is obscure. Possibly they serve the 

 same function as the prostate gland. The small glands of liittrc 



