Il8 CARL R. MOORE. 



to show the structural condition of the testis shortly after birth. 

 It can be seen that this 1 7-day normal guinea pig testis consists 

 of seminiferous tubules that show little or no tendency to produce 

 an active germinal epithelium. The testis is essentially of the 

 embryonic type and differentiation into the different elements of 

 the germinal line does not occur until considerably later. When 

 such a testis as this is confined to the abdomen it tends to remain 

 in about the same stage of differentiation for several months 

 and in fact after two years abdominal retention quite a similar 

 picture is presented, provided the opposite testis is a normal one. 

 If, however, both testes are confined to the abdomen, this 

 characteristic embryonic type is not retained. 



FIG. 2. Seminiferous tubules from a guinea pig testis (144/1-211) elevated to 

 the abdomen thirty days after birth (unilateral cryptorchid with opposite testis in 

 scrotum) and removed 45 months later. (Same magnification as Fig. i.) 



Fig. 2 (144^-211) is a reproduction of a few seminiferous 

 tubules from the unilateral cryptorchid testis removed from 

 animal No. 5 (see Table I.). It was elevated to the abdomen 

 on the 3Oth day after birth and remained for 4^ months (opposite 

 testis normal). Since this is approximately the average period 

 of confinement in the abdomen for all cases reported here, it 

 will serve to acquaint us with the grade of organization of all 

 such testes at the time of their replacement in the scrotum. 

 One can appreciate from Fig. 2 that although this testis was 

 removed from the animal 5^ months after birth, its structural 

 development has remained essentially that of the normal testis 



