470 



Eben Clayton Hill. 



is "rational." If a student knew that the vessels entered the 

 mediastinum and also penetrated the substance of the gland through 

 branches from the capsular artery, he could readily picture the 

 distribution of these vessels. In the pig testis the vessels enter from 

 the capsule, but form most unusual loops. Reference to my former 

 article on the pig's testis^ will serve to bring out the contrast with 

 the arrangement in man; both in the penetrating vessels and their 

 branches and in the supply to the albuginea, etc. 



Practically the whole blood supply of the testis of the pig 

 comes from one large capsular artery which encircles the gland 

 sending tortuous rib-like branches around it. These branches send 

 other branches deep into the gland to the mediastinum without giv- 



FiG. 4. — Isolated artei-ies of human adult testis. These vessels were hi- 

 jected with celloidin and the testis was then digested in HCl and pepsin. 



X 21/2. 



ing off any branches, then loop back and supply the tubules through 

 the return loops. This unique arrangement may be occasioned by 

 the central location of the mediastinum (Fig. 5) which is so essen- 

 tially different from the lateral location of this collecting portion 

 of the human testis. 



A cross section of the fresh testis gives an impression that very 

 thick, strong trabeculae pass from the mediastinum to the albu- 

 ginea giving the appearance of a fan. That these are trabeculae 



Fig. 5.— Sagittal section through testis of adult pig to show central location 

 of mediastinum. E., epididymis ; M., mediastinum ; S. C, spermatic cord. 



