THE MALE ORGANS OF GENERATION. 235 



mis and tunica vaginalis, form several large trunks, which fol- 

 low the spermatic cord. Distinct networks of lymphatic ves- 

 sels are found in the vascular and nervous layers of the sper- 

 matic cord, and some are seen close to the muscular coat of the 

 vas deferens. 



The seminal vesicles, designed as receptacles for the fluid 

 secreted by the testicles, are, with some slight modifications, 

 similar in structure to the vas deferens. They are composed 

 of a mucous, muscular, and fibrous coat. The mucous mem- 

 brane is covered with a superficial layer of cylindrical and a 

 deep layer of polyhedral-epithelial cells, and is thrown into 

 folds, longitudinal and transverse, forming depressions. The 

 muscular coat consists of three layers, an internal or longi- 

 tudinal, a middle or circular, and an external or longitudinal. 

 The fibrous coat is abundantly supplied with networks of ves- 

 sels and nerves. Here the ganglionic collections are highly 

 developed, each corpuscle being quite large and containing a 

 single nucleus, or even at times two. 



The ejaculatory ducts are, histologically, similar to the last 

 described organs. As they approach the prostate their cylin- 

 drical epithelium gradually changes into the transitional va- 

 riety, and subsequently into the laminated pavement, as they 

 approach their point of outlet in the urethra. Their mucous 

 membrane is uneven from the longitudinal and transverse 

 folds. After entering the prostate the muscular substance of 

 the ducts undergoes cavernous transformation. 



When the testicle attains its full physiological develop- 

 ment, which occurs in man at puberty, there is secreted by the 

 organ a peculiar fluid, the semen or sperma. This fluid is 

 whitish, slimy, and colorless, and has an alkaline or neutral re- 

 action. Semen examined as discharged from the orifice of the 

 urethra, in coitu, appears as a very different fluid, having re- 

 ceived the secretions from the various accessory glands of the 

 generative system. It is now more fluid, opaque, strongly al- 

 kaline in reaction, and has acquired a peculiar odor. Placed 

 under the microscope there is seen suspended in a hyaline fluid 

 an infinite number of moving thread-like bodies called seminal 

 filaments, spermatozoa, spermatozoids, seminal elements, etc. 

 They are divided into a head, body or middle portion, and tail. 



