496 ANDREW T. RASMUSSEN 



In mid-summer the testis again decreases. Figures 20, 21 

 and 22 show the conditions during the earUer stages of the 

 retrogression. In the particular case from which these figures 

 were taken, the testis represented only 0.038 per cent of the 

 reduced body weight, much of the fat already having been 

 absorbed, as is evident from figure 22 which is to be compared 

 directly .with figure 18. The fat which is left is found as rather 

 large globules only a few of which are found in one cell as com- 

 pared with the numerous globules present earlier. During 

 this atrophy the interstitial cells are undergoing profound 

 modifications. Pigment granules are increasing due to a chemi- 

 cal transformation of some of the fatty material into a pigmented 

 compound. A number of the ordinary interstitial cells do not 

 decrease much in size but all the fatty globules within them 

 become changed to this pigment. 



Spermatogenesis is steadily advancing. Spermatocytes are 

 increasing in number and are filling up the lumen of the tubules. 

 The testis becomes abdominal. 



By August the testis is minimal, being only 0.015 per cent of 

 the reduced body weight. The tubules are much closer together 

 (fig. 23). Most of the interstitial cells are reduced to Httle 

 more than the nuclei, which have also become smaller, many 

 being under 5 ^ in diameter. Some of the smaller nuclei tend 

 to stain more solidly, due undoubtedly, as suggested by White- 

 head ('08), to a lack of decolorization. Plato ('96) and Ganfini 

 ('02) observed that the nuclei of the nonvacuolated cells appear 

 to stain more intensely than do those of the vacuolated ones. 

 Surrounding one-half of the nucleus there is in the scanty cyto- 

 plasm a dense cap of pigment granules as shown in figure 24. 

 If there are any of the finer lipoid granules, such as occupied the 

 dense central mass of cytoplasm before the atrophy occurred, 

 they are masked by the numerous pigment granules. The fatty 

 globules which filled the peripheral cytoplasm of the enlarged 

 interstitial cells have disappeared entirely (fig. 26). 



A number of the cells have not undergone much change in 

 size. In figure 26 they are seen as the larger c^lls with coarse 

 spherical granules ot various sizes within them. A group of 



