INTERNAL SECRETION OF TESTICLE 199 



the interstitial cells of the mammal to be derivatives of the cells 

 of lymphoid nodules disposed between the seminal tubules. A 

 similar view was held by Champy (1913) for the frog, and 

 by Courrier (1922 b) for the Gasterosteus. 



I should like to point out certain objections of a general 

 order to Goodale and Nonidez's conception. I have myself 

 no experience of birds, but what we learned in our laboratory 

 for mammals conforms with some of Nonidez's observations. 

 First, the interstitial cells in the testicle of the mammal seem 

 to be of very different types; a glance at Fig. 56 (especially g) 

 conveys this idea. The size, shape and inclusions of the 

 interstitial cells are manifold. Further, a detailed research on 

 the inclusions of the interstitial cells of the mammals, which 

 Wagner has undertaken in our laboratory, also gave some 

 cytological results very similar to those of this author. But 

 we may still ask whether there is sufficient evidence for the 

 claim that the different types of interstitial cells are merely 

 elements common to all other organs. What is proved by 

 Nonidez is only the fact that the different types of interstitial 

 cells may be derived, like the blood cells, from mesenchyme cells, 

 and further that the interstitial cells are cytologically very 

 similar to cells common to other organs. This does not mean 

 that the interstitial cells can be identified with certain types of 

 blood cells or with similar cells in other organs in regard to their 

 function. I agree that the question as to the function of the 

 interstitial cells in birds and their bearing on the internal 

 secretion of the testicle is a very complex one, more complicated 

 than it might seem at first. The cytologist will play an im- 

 portant part in the elucidation of this question. But it would 

 be a great mistake to build up a theory as to the seat of hormone 

 production in the testicle on the basis of morphological 

 observations only. It may be also mentioned that according to 

 Nonidez (1922) certain interstitial cells in birds are formed 

 from young seminiferous tubules which undergo degeneration. 

 Benoit (1923 b) is even of the opinion that possibly all inter- 

 stitial cells arise in the cock during embryonic development 

 and during youth in a similar manner, i.e., that they are all 

 of an epithelial origin. 



A new paper of Ceni (1922) may be mentioned here. He 

 claims to have given new proofs of the endocrine function of 

 the generative part of the testicle in the cock. 



