264 R. R. HUMPHREY 



interference with the normal circulation through the interlobular 

 vessels. In other animals (e.g., woodchuck, mole, corvus) in 

 which there is a marked change in the volume of the testis 

 following spermatogenesis, the reduction in size of the tubules is 

 accompanied by such growth of interstitial cells as to prevent 

 complete collapse of the organ. In the mammalian ovary, 

 similarly, the development of interstitial cells around atretic 

 follicles and the hypertrophy of follicular and stromal elements 

 during the formation of the corpus luteum may meet a mechani- 

 cal need, even though the existence of such a need is not of itself 

 sufficient to initiate the growth processes mentioned. Chemical 

 as well as mechanical factors are involved, and the impossibility 

 of separating the two stands in the way of any determination of 

 their relative importance. 



Biedl says: ''If we summarize all that is known concerning 

 the internal secretory tissue of the male genital gland, we are 

 led to the inevitable conclusion that the hormone which gives to 

 the organism its male characteristics, is elaborated in the cells 

 of Leydig in the interstitial tissue. . . . We are justified 

 in describing them in their totality as an interstitial gland." 



The writer does not wish to be understood as asserting the 

 inapplicability of this statement to urodeles. Other structures 

 of the vertebrate body having, in their original state, as little 

 adaptation for glandular activity, develop into endocrine organs 

 of more or less recognized status. Hence, despite the conditions 

 which invariably call the interstitial cells of urodeles into being, 

 there is yet the possibility that their lipoids or degeneration 

 products, after entering the circulation, are capable of influencing 

 the organism in specific ways, either alone or in combination 

 with other testicular elements. It seems desirable, however, 

 to offer a few brief comments on the relations of the interstitial 

 cells to which one might look for confirmation of their supposed 

 secretory function in the urodeles. 



Morphologically, they do not possess the usual relations of 

 an endocrine gland with respect to blood vessels. They develop 

 primarily around the lobule; any relation to the blood vessel 

 is secondary and incidental — i.e., through crowding. Though 



