190 CARL G. HARTMAN AND WILLIAM F. HAMILTON 



tained in them ordinary fat of metabolism, as Pearl and Boring 

 ('12) contend, further study must determine. Massaglia ('21) 

 tacitly homologizes these cells by calling them the 'cells of 

 Ley dig.' 



On the mammalian side there is more definite information on 

 these details, for here it is possible to destroy the germinal 

 portion of the testis (leaving the interstitial not only intact, 

 but even hypertrophied) by taking advantage of the differential 

 susceptibility of these two elements to certain harmful stimuli: 

 to radiation (Steinach and Holzknecht, '16), to alcohol (Kostitch, 

 '21), to the pressure due to ligation of the vas deferens (Steinach, 

 '12, '21). Similar experiments done on fowl might lead to illumi- 

 nating results. Several workers have ligated the vasa deferentia 

 of roosters, but with conflicting results. Shattock and Seligmann 

 ('04) find that ligation of the vas does not interfere with the sper- 

 matogenesis nor does it produce any germinal degeneration. This 

 is, of course, rather to be expected, in view of the fact that healthy 

 testicular transplants in fowl, unlike those in mammals, always 

 contain spermatozoa (Guthrie, Goodale). The present writers 

 repeated the experiment in one case with the identical results 

 obtained by Shattock and Seligmann. Massaglia's recent ex- 

 periments ('21), however, yielded different results, for in those 

 animals in which the vas remained occluded the testis gradually 

 atrophied in all of its elements except the 'cells of Ley dig,' which 

 in themselves, according to the author, sufficed to maintain 

 male sex characters (comb and wattles) and behavior. 



To summarize, then, it seems to us, first, that the 'luteal' 

 cells of the ovary are very likely the ones responsible for a part of 

 the female hormones of that organ and, second, that we cannot 

 with certainty identify the endocrine cells of the testis. In the 

 next section some of the theoretical bearings of these conclusions 

 will be discussed. 



