550 THE TISSUES. 



onic areolar tissue; producing atrophy of the Malpighian bodies 

 by its pressure, and thus interfering with the functions of the gland. 

 6. The casts of the uriniferous tabes, occurring in various con- 

 ditions of the kidney, have already been noticed (Figs. 123-4, and 

 p. 215). Another form is also shown by Fig. 379. 



CHAPTER XY. 



THE SEXUAL OKGANS. 



I. SEXUAL APPARATUS OF THE MALE. 



THE male sexual organs are: 1. The testes; 2. The vasa defe- 

 rentia; 3. The vesiculaB seminales and ejaculatory ducts; 4. The 

 penis, including the urethra and the accessory glands (Cowper's and 

 the prostate). The mucous membrane of the urethra, prolonged 

 through the vesicula seminalis and the vasa deferentia to the semi- 

 niferous tubes of the testis, constitutes the genital passages of the 

 male. 



1. The urethra is a canal of mucous membrane, supported through- 

 out its spongy portion by the corpus spongiosum urethrce, and in the 

 prostatic by the prostate gland ; while the membranous portion, so 

 called, is an independent canal. The corpus spongiosum is essen- 

 tially of the same structure as the corpus cavernosum penis, next to 

 be described ; except that its investing fibrous membrane is much 

 thinner and has more elastic fibres, the intertrabecular spaces are 

 smaller, and the trabeculas are smaller and richer in elastic fibres 

 beneath their epithelium. It is also invested externally by a layer 

 of smooth muscular fibres, and expands into the glans penis at its 

 free extremity. 



The mucous membrane of the prostatic and membranous por- 

 tions contains smooth muscular fibres, both longitudinal and trans- 

 verse, though less developed in the membranous portion; and 

 outside of these, in the latter, are the striated fibres of the accelerator 

 urince muscle. Smooth fibres also exist here and there in the sub- 

 mucous tissue of the spongy portion, and a complete muscular tunic 

 formed of them lies in contact with the corpus spongiosum on its 



