2.66 



THE QUARTERLY REVIEW OF BIOLOGY 



DISCUSSION 



When the data on fishes are carefully 

 assembled no correlation is found between 

 the volume of the interstitial cells and 

 time of sex activity. Such a parallelism 

 was reported by Courrier, but Champy 

 and Van Oordt have both shown this to 

 be an error. In Amphibia such a parallel- 

 ism was reported by Friedman and by 

 Mazzetti for Rana fusca, Rana viridis, and 

 Hyla arborea. When the data have been 

 carefully analyzed it becomes apparent 

 that the interstitial cells reach their 

 maximum volume some time after mating. 

 Champy failed to find a parallelism be- 

 tween interstitial cell volume and sex 

 activity and sought other possible parallel- 

 isms. Humphrey has shown that in 

 urodeles the interstitial cell increase is 

 related to emptying of lobules and not to 

 sex activity. Aron stresses the presence 

 of Sertoli cells in the "Glandular masses" 

 which alone form the hormone in urodeles. 

 In birds it is certain that the interstitial 

 cells do not increase in volume before or 

 during the period of sex activity. They 

 are most abundant when sex activity is 

 least evident. In mammals the evidence 

 is indicative of the same relationship. It 

 was pointed out above that Marshall 

 found an interstitial cell increase during 

 spermatogenic activity in the Hedgehog. 

 The interstitial cells increase before sex 

 activity and decrease during hibernation. 

 Rasmussen reported that in Marmot a monax 

 there is an increase of interstitial cells that 

 begins before mating. But the interstitial 

 cells are most abundant at the time of or 

 after birth of the young. The maximum 

 volume therefore lags behind actual mat- 

 ing rather than precedes it. Ganfini 

 found that in Marmota marmota the inter- 

 stitial cells were as abundant during 

 winter as during the sexually active 

 period. There is then no real parallelism 



between sex activity and interstitial cell 

 volume in Marmota. In the mole it is 

 certain that the interstitial cells are least 

 abundant during the mating season. 

 They increase when spermatogenesis is 

 arrested, and this is after mating. 



It is therefore clear that there is no 

 constant parallelism between sex activity 

 and interstitial cell quantity. In fact 

 there is in most cases an inverse relation- 

 ship. The only exceptions to this state 

 of affairs are in Erinaceus eurofeus and 

 possibly in Marmota monax. In the former 

 an exact relationship between sex activity 

 and interstitial cell quantity is reported, 

 while in the latter the interstitial cell 

 increase begins during the period of sex 

 activity and reaches its maximum after 

 young are born. It appears more reason- 

 able to claim that the parallelism found in 

 these two species is an accidental relation- 

 ship while that found in all other species 

 cited above is typical rather than to 

 use these two species as typical of 

 vertebrates. 



The inverse relationship between sexual 

 activity and quantity of interstitial cells 

 takes on added importance when it is 

 noted that there is a decrease in or abey- 

 ance of sexual activity at the time that the 

 interstitial cells increase. In some species 

 they are present only during the season of 

 sex inactivity. Nor should their entire 

 absence in certain species be overlooked. 

 These facts stand in direct opposition to 

 the interstitial cell secretory theory. 



In the group of animals in which the 

 interstitial cells are present only during the 

 period of sex inactivity it might be argued 

 that the hormone is effective only after a 

 certain latent period. There are no data 

 available that show how long it takes the 

 hormone to become effective, but it is 

 known that its absence is evident in 5 to 

 iz days in rats (Hoskins, 2.0) and in about 

 the same period in birds when determined 



