On the Interstitial Cells in Testicle of Guinea-Pig . 135 



interstitial cells; in a small testicular fragment is not very much augmented, 

 so that the number of the interstitial cells is highly diminished in com- 

 parison with those in a normal testicle. 



B. In the experiments with partial castration on guinea-pigs, mentioned 

 above, we used in reality two different methods. In some of these experi- 

 ments we left in the body, as *previously said, a small segment of the upper 

 pole of one testicle. In other experiments of this series we left a segment 

 of the under pole of the testicle above the cauda epididymidis. In the 

 latter we never saw the enormous hypertrophy of interstitial cells observed 

 in some cases of " upper " partial castration, although in " under " partial 

 castration a marked increase in the number of interstitial cells occurs. But 

 the " under " testicular fragment degenerates, in general, so far as to become 

 sclerotic, whereas the upper fragment can resist longer against sclero- 

 sation(llA). We explain this dissimilitude by a difference in the blood 

 supply in the two methods. In the " under " partial castration the testicular 

 fragment is supplied with blood by the arteria deferentialis, the artery of 

 the vas deferens, which gives off branches from the under part of the 

 testicle. These branches, as is known in human anatomy, have an anasto- 

 mosis with the branches of the arteria spermatica interna supplying the upper 

 half of the testicle. The art. def. is a small one in comparison with the 

 art. sp. i., and we supposed that in our experiments the blood supply of 

 an upper fragment was better than the blood supply of an under 

 fragment. We found the plexus pampiniformis unchanged, so that it is 

 very probable that a small upper testicular fragment received the same 

 quantity of blood from the art. sperm, int. as the whole testicle. We think 

 it right to conclude from these observations that the good blood supply 

 explains, in a sufficient manner, the great development or the hypertrophy 

 of the interstitial tissue in upper testicular fragments as related above. 



C. Experimental evidence that the latter conclusion is true, and that the 

 hypertrophy of the interstitial cells in the upper testicular fragment is caused 

 by local conditions, is shown by the following observations. On six guinea- 

 pigs of different ages the one testicle was cut into two fragments, both of 

 which were left in the body ; the upper one supplied by the art. sp. i., the 

 under one supplied by the art. defer. (On the other testicle we made — for 

 other experimental purposes — incisions going through about half or more of 

 the testicle, but not touching the ductus epididymidis.) All these animals 

 showed during four months of observation normal somatic sexual characters. 

 A rtsumi of the six experiments we performed is given in the following- 

 Table :— 



