542 E. V. COWDRY 



at the expense of the mitochondria. Hie claims that, as the interstitial cells 

 develop and become charged with lipoid droplets, there is a proportionate 

 diminution in the number of mitochondria, and that he has been able to 

 follow all the stages in the chemical transformation of the mitochondrial 

 substance into the lipoid droplets. In another place I have pointed out 

 the danger of making such a broad assertion (Cowdry, '18, p. 102). 



As far as our observations go, the mitochondria in the interstitial cells 

 exhibit no special peculiarities. They are cytoplasmic constituents of a 

 generalized type. 



Hortega ( 7 13) and Cattaneo ('14) have carefully described the 

 reticular apparatus, without bringing to light any special features dis- 

 tinctive of the interstitial cells. Inasmuch as it has been impossible thus 

 far to study this structure in living cells, and since the technic for its 

 demonstration in fixed preparations is notoriously unreliable, it will be 

 advisable to postpone a discussion of its possible relationship to secretory 

 activity until we have more information to go on. 



It is interesting to note, in connection with the existence of a prob- 

 lematic homology between the interstitial cells of the ovary and those of 

 the testis, that Aime has found cells containing xanthin in the ovary of 

 fetal horses bearing a close resemblance to the xanthochrome cells of the 

 testis originally described by Bouin and Ancel. Nevertheless, it is safe 

 to say that, on the whole, pigments are of rare occurrence in the interstitial 

 cells of the ovary. 



At present the majority of investigators are inclined to believe that 

 the interstitial cells of the ovary produce a lipoidal secretion in common 

 with those of the testis and the cortical cells of the suprarenal gland, for 

 which the lipoid granules, above mentioned, are usually regarded as the 

 secretion antecedent. As far as we can tell, the discharge of these granules, 

 if it does take place, is not under nervous control. 



Mulon has discovered that the cytoplasm often stains diffusely and 

 intensely with iron hematoxylin and other dyes. He observed the same 

 reaction in the interstitial cells of the testis and the cortical cells of the 

 suprarenal, and is inclined to interpret it as indicating the presence of 

 diffuse lipoidal secretion antecedent in solution, which he believes to have 

 been formed from mitochondria. I am unable to agree with him in this 

 explanation, because I have found that the cells of the central nervous 

 system often exhibit a similar appearance, which I have provisionally 

 attributed to a swing of the reaction in them toward the acid side. 



Van der Stricht's ('12) investigations of the mode of secretion in the 

 bat are very enlightening. He was able to follow successive stages in the 

 formation of clear droplets within the fatty globules of the interstitial 

 cells, as is illustrated in Fig. 3. These, he claims, pass out of the cells 

 into the intercellular spaces, thence into the lymphatics, and ultimately 

 into the general circulation. His drawings are very suggestive, showing, 



