682 REPRODUCTION. 



and are sometimes known by the name of the " false kidneys." There 

 is little doubt that they perform, at this period, a function analogous to 

 that of the kidneys, and separate from the blood of the embryo an 

 excrementitious fluid which is discharged into the cavity of the allantois. 

 Subsequently, the Wolffian bodies increase in size ; but as they 

 grow less rapidly than the other organs, their relative magnitude dimin- 

 ishes. Still later, they suffer an absolute atrophy, and become less per- 

 ceptible. In the human embryo, they are hardly visible after the second 

 month (Longet), and in the quadrupeds they disappear long before 

 birth. 



The kidneys are formed just behind the Wolffian bodies, by which 

 they are at first concealed in a front view, the kidneys being at this 



time not more than one-fourth or one-fifth 

 FIG. 230. part the size of the Wolffian bodies. (Fig. 



230.) The kidneys subsequently enlarging, 

 while the Wolffian bodies diminish, the pro- 

 portion between the two organs is reversed ; 

 and the Wolffian bodies appear as small 

 ovoid or fusiform masses, on the anterior 

 surface of the kidneys (Figs. 231 and 232), 

 As the kidneys grow more rapidly in an 

 upward than a downward direction, the 

 Wolffian bodies come to be situated near 

 their inferior extremity. 

 ^*, ^^, .- ^^www*^ The k j dnc y g> Curing the succeeding periods 

 i. Wolffian body. 2. Kidney. of festal life, become very largely developed 

 in proportion to the rest of the internal or- 

 gans ; attaining a size, in the foetal pig, equal to more than two per 

 cent, of the entire body. This proportion again diminishes before birth, 

 owing to the increased development of other parts. In the human 

 foetus at birth, the weight of the two kidneys together is six parts per 

 thousand of the entire body. 



Internal Organs of Generation. About the same time with the 

 formation of the kidneys, two oval-shaped organs make their appear- 

 ance in front, on the inner side of the Wolffian bodies. These are the 

 internal organs of generation ; namely, the testicles in the male, and 

 the ovaries in the female. At first they occupy the same situation and 

 present the same appearance, whether the totus be male or female (Fig. 

 231). 



A short distance above the internal organs of generation there com- 

 mences, on each side, a narrow tube which runs downward, parallel 

 with the excretory duct of the Wolffian body. The two tubes approach 

 each other below ; and, joining upon the median line, empty into the 

 base of the allantois, or what will afterward be the urinary bladder. 

 These tubes serve as the excretory ducts of the internal organs of 

 generation ; afterward becoming the vasa deferentia in the male, and 

 the Fallopian tubes in the female. According to Coste, the vasa 



