HUMAN TESTIS AND EPIDIDYMIS 399 



the greater number of convolutions, the conditions are similar 

 to those found at seven months. 



From the diagram we see that there are to be found tubules 

 with no connections whatever, except that with the rete, ending 

 blindly; others with several branches which end blindly; others an- 

 astomosing with their neighbors. In one a short blunt knob, x, 

 was seen (found also in the adult testis) such as has been described 

 as commonly present by some authors. But to me the most in- 

 teresting part of the diagram is the preservation, at seven months 

 and probably in the adult, of the course, connections, and position 

 of each tubule as determined for it by the original network of the 

 testis cords. 



THE BLOOD VESSELS 



Hill has described the development of the blood vessels of the 

 testis in the pig, and in a later work has apparently taken for 

 granted that, although the adult arrangement in pig and man 

 differ widely, the early development is similar in each case. In 

 the pig the spermatic artery arises as a separate vessel from the 

 dorsal aorta, caudal to the last mesonephric artery, or rarely as 

 a branch of the latter. It makes its way horizontally to the 

 mesial border of the Wolffian body, and then turns upward, toward 

 the head, passing mesial to the mesonephric arteries, and crossing 

 over the last five or six of them, to reach the genital gland ; it thus 

 approaches the testis from the caudal end. In man there is no 

 such vessel formed. The arteries to the Wolffian glomeruli in 

 the region of the future testis send branches to supply the gland 

 directly, so that at first there are many spermatic arteries, which 

 enter all along the attachment of the testis to the Wolffian body. 



On examining embryos of other mammals in regard to the 

 origin of their spermatic arteries, I find that in sheep, rabbit, cow, 

 and deer (cervus capreolus) a separate vessel is formed to supply 

 blood to the genital gland, whether it be testis or ovary; while in 

 the cat the arteries to the glomeruli send branches directly to the 

 gland. In sheep, the new artery is more apt to arise as a branch 

 of the last mesonephric artery than as a direct outgrowth from 

 the aorta, and in one deer embryo of 19.6 mm. (H. E. C, no 1230) 



