928 GENERATION. 



Wolffian ducts. In the female, their upper extremities remain free, except the single 

 fimbria which is connected with the ovary. Their inferior extremities unite with each 

 other, and, at their point of union, they form the uterus. When this union is incomplete, 

 we have the malformation known as double uterus, which may be associated with a 

 double vagina. The Wolffian bodies and their ducts disappear, in the female, at about 

 the fiftieth day. A portion of their structure, however, persists, in the form of a col- 

 lection of closed tubes, constituting the parovarium, or organ of Rosenmtiller. 



In the female, the ovaries pass down no farther than the pelvic cavity ; but the testi- 

 cles, which are at first in the abdomen of the male, finally descend into the scrotum. 

 As the testicles descend, they carry with them the Wolffian duct, that portion of the 

 Wolffian body which is permanent constituting the head of the epididymis. At the 

 same time, a cord appears, attached to the lower extremity of the testicle and extending 

 to the symphysis pubis. This is called the gubernaculum testis. It is at first muscular, 

 but the muscular fibres disappear during the later periods of utero-gestation. It is not 

 known that its muscular structure takes any part, by contractile action, in the descent 

 of the testicle in the human subject. The epididymis and the vas deferens are formed 

 from the Wolffian body and the Wolffian duct. 



At about the end of the seventh month, the testicle has reached the internal abdom- 

 inal ring ; and, at this time, a double tubular process of peritoneum, covered with a few 

 fibres from the lower portion of the internal oblique muscle of the abdomen, gradually 

 extends into the scrotum. The testicle descends, following this process of peritoneum, 

 which latter becomes eventually the visceral and parietal portion of the tunica vaginalis. 

 The canal of communication between the abdominal cavity and the cavity of the scrotum 

 is finally closed, and the tunica vaginalis is separated from the peritoneum. The fibres 

 derived from the internal oblique constitute the cremaster muscle. 



At the eighth or the ninth month, the testicles have reached the external abdominal 

 ring and then soon descend into the scrotum. The vas deferens, as we have seen, passes 

 from the testicle, along the base of the bladder, to open into the prostatic portion of 

 the urethra; and, as development advances, two sacculated diverticula from these tubes 

 make their appearance, which are attached to the bladder and constitute the vesicular 

 seminal es. 



As the ovaries descend to their permanent situation in the pelvic cavity, there appears, 

 attached to the inner extremity of each, a rounded cord, analogous to the gubernaculum 

 testis. A portion of this, connecting the ovary with the uterus, constitutes the ligament 

 of the ovary ; and the inferior portion forms the round ligament of the uterus, which 

 passes through the inguinal canal and is attached to the symphysis pubis. 



The development of the external organs of generation will be studied after we have 

 described the development of the urinary apparatus. 



Development of the Urinary Apparatus. Behind the Wolffian bodies, and developed 

 entirely independently of them, the kidneys, suprarenal capsules, and ureters make their 

 appearance. The kidneys are developed in the form of little, rounded bodies, composed 

 of short, blind tubes, all converging toward a single point, which is the hilum. These tubes 

 increase in length, branch, become convoluted in a certain portion of their extent, and 

 finally assume the structure and arrangement of the renal tubules, with their Malpighian 

 bodies, blood-vessels, etc. They all open into the hilum. At the same time that the kid- 

 neys are undergoing development, the suprarenal capsules are formed at their superior 

 extremities. These bodies, the function of which is unknown, are relatively so much 

 larger in the foetus than in the adult, that they have been supposed to be peculiarly 

 important in intra-uterine life, though nothing definite is known upon this point. The 

 kidneys are relatively very large in the foetus. Their proportion to the weight of the 

 body, iii the fcetus, is 1 to 80, and, in the adult, 1 to 240. The ureters are undoubtedly 

 developed as tubular processes from the kidneys, which finally extend to open into the 



