THE TESTES. 401 



with the tunica vaginalis, a serous sac derived from the 

 peritoneum. The tunica albuginea is the white, fibrous, 

 investing structure of the testis ; it sends off fibres from 

 the upper surface of the testicle, forming an incomplete 

 septum, and also trabecula3, which support the glandular 

 structure. The tunica vasculosa consists of a plexus of 

 capillaries, which lines the inner surface of the tunica 

 albuginea. The testes are tubular glands ; the tubuli are 

 highly convoluted, each about eight feet in length, and 

 about five hundred in number; they are about T 7 inch 

 in diameter, and consist of a basement membrane, upon 

 which are several layers of cells ; the cells of the inner- 

 most layer become fibrillar, and undergo transformation 

 into the spermatozoa, which are simply modified epithe- 

 lial, ciliated cells. 



The tubules, in groups of from three to five, are in- 

 closed in delicate fibrous tissue, derived from the tunica 

 albuginea ; each group constitutes a lobule ; near the ter- 

 mini of the tubules they become straight, and unite to 

 form twenty or thirty larger ducts, each about one- 

 fiftieth inch in diameter, which run along the upper 

 border to the head of the epididymis ; these larger ducts 

 are called the vasa recta and unite so as to form about 

 fifteen vessels, which perforate the tunica albuginea and 

 become convoluted, forming the globus major of the epi- 

 didymis. Each convolution of the globus major con- 

 sists of a tubule six or seven inches long, and these 

 open into a large, single, highly-convoluted tube, which 

 forms the body and globus minor of the epididymis. So 

 extraordinary are the convolutions of the tube forming 

 the body and tail of the epididymis, that it measures, 

 when carefully unraveled, about twenty feet. The globus 

 minor terminates in the vas deferens. It is a strong, 

 fibrous duct, which feels not unlike a whip-cord, and is 



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