MARSUPIAL SPERMATOGENESIS 213 



resulting fluid, I could not be absolutely certain whether the 

 rods were dissolved or not, although in the majority of cases 

 the rods were still visible. 



Bardeleben refers to these bodies as crystals of haematoidin. 

 He also describes the presence of similar bodies in the great 

 blood lacunae in the material of the testis. With regard to the 

 composition of these bodies I have not been able to determine 

 whether they are composed of haematoidin or not. 



Fresh tissue was boiled in chloroform. The tissue was then 

 embedded and sections cut, stained, and mounted. Upon 

 examination it was found that in no case did the chloroform 

 have any action on the rods in the Sertoli cells. 



This does not of course confirm Bardeleben's view that they 

 are crystals of haematoidin, but goes to show that they are, 

 at any rate, not a blood derivative which is an acid. 



With regard to the occurrence of similar bodies in the blood 

 lacunae of the testis, in all the material I have examined I have 

 not found any bodies comparable with the rods found in the 

 Sertoli cells. The presence of somewhat similar rods has been 

 described by several authors. Montgomery has shown that the 

 Sertoli cells in man are derived from the spermatogonia, and 

 that the nature of the resultant cell is determined by the 

 presence of a rod-like body in the cytoplasm, i. e. all spermato- 

 gonia! cells containing the rod-like body give rise to the Sertoli 

 cells. This, however, does not appear to be the case in 

 Phascolarctus. Although I am convinced that the Sertoli 

 cells in Phascolarctus arise from a division of the spermato- 

 gonia, I have never been able to find any trace of the rods until 

 the nucleus of the cell, by its peculiar structure, is definitely 

 defined as a Sertoli cell. No Sertoli cell divisions have been 

 found in Phascolarctus, but in Perameles (in this 

 animal the Sertoli cells are comparable with Phascolarctus 

 in point of size and nuclear structure) I have found an apparent 

 diplotene nucleus which from its size and position in the 

 tubule appears to have originated from a Sertoli nucleus. 

 From this it seems safe to assume that the Sertoli cell has been 

 derived from the same cells as give rise to the germ cells. 



