136 KANSAS UNIVERSITY SCIENCE BULLETIN. 



The total of 313 counts from sections 30, 35, and 40 micra 

 thick are: 



29 groups of 6 spermatozoa. 



77 groups of 7 spermatozoa. 



106 groups of 8 spermatozoa. 



76 groups of 9 spermatozoa. 



18 groups of 10 spermatozoa. 



6 groups of 11 spermatozoa. 



1 group of 12 spermatozoa. 



In two cells which appeared to be whole only 5 spermatozoa 

 could be made out, and a few times, especially among immature 

 spermatozoa, groups were so close together as at first to ap- 

 pear as one, thus forming groups of more than twelve. It is 

 possible that groups of 5 or 13 or 14 do occur, but if so, they 

 are very rare. From these counts and the earlier ones it is 

 evident that the number of spermatozoa to each Sertoli cell in 

 the rat varies from 6 to 12 and is oftener 7, 8 or 9. 



The rod or crystal which Montgomery and Winiwarther de- 

 scribe is not visible in the human material studied, but this 

 can doubtless be accounted for in the fixation. The Sertoli 

 cell nuclei stain darkly and are always irregularly shaped and 

 distributed. The Sertoli cells of the cat testes on the contrary 

 do show rods and rodlets, in the tissue preserved in Tellyes- 

 niczky's fluid as well as that preserved in Flemming's fluid. 

 These rods are, presumably, structures similar to those of hu- 

 man Sertoli cells for they are long and slender, sometimes 

 curved, and irregularly placed. They are, however, not as dis- 

 tinct as those of the human testes as illustrated by Montgomery 

 and Winiwarther. It is only with very careful focusing that they 

 can be seen at all, and a few times this focusing has made them 

 appear to be corners or edges of the nuclear membrane. With 

 their irregularly shaped nuclei this might indeed be possible. 

 Winiwarther, although, he calls these structures crystals, and 

 has discussed them at some length, has been unable to prove 

 their crystalline properties by polarization of light and even 

 says that he has never been able to identify with certainty these 

 crystals of Charcot. Besides the rod or crystal, both authors 

 describe rodlets or accessory strips (batonnets), which Mont- 

 gomery says persist longer, while Winiwarther says the rods 

 persist after the rodlets disappear. The rods have been seen 

 after the Sertoli nuclei were well pushed away from the wall of 

 the cat testes. 



