On the Interstitial Cells in Testicle of Guinea -Pig. 137 



As we see from the weight of the animals used for these experiments, they 

 were all at an age when the spermatogenesis in guinea-pigs has attained a 

 very high degree, or when the production of spermatozoa begins ; some of 

 them were adult animals. 



The result of these experiments is that in all the six cases there was, four 

 months after the operation, a very marked degeneration of the under 

 fragment of the operated testicle. This degeneration concerned both the 

 seminiferous and the interstitial part of the testicular fragment, the latter 

 being transformed more or less completely into connective tissue. Having 

 observed a great number of testicles under different experimental conditions, 

 I should like to mention here that there seem to be different forms of 

 degeneration which the testicle rimy undergo ; but I have not enough insight 

 into this field of pathological anatomy to judge on this question. 



Unlike the under fragment, the upper fragment was, in four cases, still 

 resisting degeneration and sclerosation. No. 69 showed in the upper frag- 

 ment, four months after the operation, tubules with spermatozoa which 

 were even present in the caput epididymidis. Other tubules in this 

 fragment were in the state of desquamation or in the juvenile stage. 

 In No. 70 all tubules are in the juvenile stage, corresponding to that of 

 an animal about three weeks old. In agreement with Benda (11b), we 

 mentioned in another paper that it is in reality not justifiable to speak about 

 a " degeneration " of the seminiferous tubules occurring after ligature or 

 section of the vas deferens, transplantation, radiation, and so on. There is 

 in reality only a process which leads up to a juvenile stage, a process which 

 occurs in an indefinitely smaller measure also in the normal testicle. To 

 understand that there is no other change than a return of seminiferous 

 tubules en masse to a juvenile stage, it suffices to compare a preparation of 

 No. 70 with one of a normal animal about three weeks old, as given in 

 Plate 1, fig. 2. I do not think that this " backward development," to use a 

 notion of Eugen Schulz (11c) is the only possible way of reaction of the 

 seminiferous tubules in different experimental conditions, and I do not think 

 that a seminiferous tubule which has returned to a juvenile stage will 

 always have the same destiny or life-history as a juvenile tubule in a normal 

 testicle ; on the contrary, in our upper fragments and in other experimental 

 cases we several times observed complete degeneration of such tubules. 

 Evidently, the same experimental condition which may lead to backward 

 development may also lead to complete degeneration of these juvenile 

 tubules. 



In No. 64 the upper fragment showed about the same condition as No. 69 

 Some tubules showed spermatozoa, others were in the juvenile stage. Beginning 



