THE SEXUAL ORGANS. 635 



by a process not as yet accurately explained, the testes, with its perito- 

 neal investment, descends into the scrotum under the agency of the 

 gubernaculum, a process composed of transversely striated and smooth 

 muscles ; and by the growing together of the peritoneal protrusion 

 contained in the gubernaculum the processus vaginalis peritoncei, 

 with its own proper serous coat, acquires its tunica vaginalis propria. 

 The vesicula prostatica, the analogue of the uterus, and probably of 

 the vagina, is the remainder of the " Mullerian ducts," two canals, 

 descending on the external border of the Wolffian body, which, in the 

 female, form the oviduct and by the coalescence of their extremities, 

 the uterus and vagina ; but in the male disappear, except the com- 

 mencement, which becomes the " hydatids of Morgagni," and the last 

 portion. The vesiculce seminales are protrusions of the v. defer entia ; 

 and the prostate, Coivpers, and the smaller glands, are most probably 

 formed, in analogy with other similar glands, from the epithelium of the 

 urethra. The penis is developed from the pelvic bones outwards, and 

 does not, till subsequently, include the urethra which is formed by the 

 closure of a groove on its inferior surface. 



With respect to the histological development of these parts little is 

 known. The testes are constituted originally of a uniform cellular sub- 

 stance, which, however, soon begins to divide into transverse rows, form- 

 ing the rudiments of the seminal tubes. These are, at first, straight 

 csecal canals, extending from the outer border of the testis to the inte- 

 rior, which most probably originate as solid tracts of cells, and only 

 subsequently acquire a cavity and membrana propria. From the con- 

 tinued growth, especially in length, of these primary channels, and the 

 production of offsets from them, the later, convoluted and very long 

 seminal tubes arise ; it appearing, in fact, that an entire lobule of the 

 testis is formed from each of them. The tunica albuginea of the testis 

 and its internal prolongations arise from the primary blastema of the 

 gland, and make their appearance at the same time with the seminal 

 tubes. 



With regard to the physiological relations of the male sexual organs, 

 in the adult, I would here notice the following points. The secretion of 

 semen, in animals, does not go on continuously, like that of the urine, 

 but is intermittent, taking place only at the time of rutting or heat. In 

 Man, the capability of producing semen, assuredly, always exists, 

 although it does not appear to follow from this, that semen is being con- 

 tinually formed, and that what is not emitted undergoes absorption ; and 

 consequently it seems justifiable to suppose that the seminal tubes secrete 

 semen only when the secretion has been partially evacuated externally, 

 either in consequence of sexual congress, or of seminal emissions, and 



nant type, the affection is " the result of morbid changes in the ducts of the rete testis ; this 

 part of the gland being the sole seat of the disease." (Curling, " Med. Chir. Transact.," 

 XXXVI. p. 456, 1853). TRS.] 



