SEASONAL CHANGES IN INTERSTITIAL CELLS 491 



The denser cytoplasm around and to one side of the nucleus 

 expands, spreading out the pigment granules (fig. 12). Vari- 

 ous stages of this expansion are well shown in figure 13. This 

 figure in comparison with figure 12 shows also that there is in this 

 newly formed dense cytoplasm a number of the fine non-pig- 

 ment granules, characteristically associated with the central 

 cytoplasm (endoplasm), as mentioned above. 



During this interstitial cell development there is no direct 

 evidence of mitotic or of amitotic cell division. Whitehead 

 ('04) in describing the rapid growth in the size of these cells, 

 as it occurs in pigs from 20 to 28 cm. in size, remarks that 

 there is no evidence of cell division after the 7 cm. stage. This 

 early cessation of signs of division in the interstitial cells of the 

 testis seems to have drawn the attention of many investiga- 

 tors. Allen ('04) found, for example, no evidence of cell division 

 after the 7.5 cm. stage in the pig, nor after eight days after 

 birth of the rabbit. Plato ('96), Finotti ('97) and Kasai ('08) 

 comment on the absence of mitosis in the interstitial tissue of the > 

 human testis. Kasai in 130 human testes, representing the wide 

 range from the four months foetus to eighty-four years, saw only 

 one mitotic figure in the interstitial cells. However, in the 

 woodchuck at this stage of rapid interstitial cell growth, such , 

 stages as are shown in figure 8 are not uncommon. Later 

 when the cells reach their maximal size, one occasionally finds 

 cells evidently containing two nuclei as shown in figure 9. In 4 

 out of 8 cases where the cells had reached their largest size, or 

 nearly so, the cells were arranged more or less in groups within 

 what appears to be a common membrane, such as is seen in figure 

 10. This would suggest that there is cell division and that 

 each group of cells represents the daughter cells of a single 

 parent cell. Von Bardeleben ('97), while not seeing any mitotic 

 figures in the interstitial cells of executed criminals, frequently 

 saw evidences of direct cell division. Von Hansemann ('95),. 

 Reinke ('96), von Lenhossek ('97) and Pick ('05), however^ 

 have reported mitotic figures in human materials, including 

 adult. 



