192 



MAULSBY W. BLACKMAN. 



telophase are more numerous in the material examined than those 

 in any other condition of the spermatogonium. A large number 

 of different stages may be distinguished. The cells in the early 

 telophase are small, while those in which the nuclear wall is re- 

 constructed are considerably larger, showing that already the 

 growth period has begun. (Compare Figs. 3 and 5.) 



With the completion of the nuclear membrane after the last 

 spermatogonial mitosis, the cells no longer belong to the first 

 division of the spermatogenetic cyde, but now contain the ma- 

 tured number of chromosomes and are spermatocytes. In insect 

 material the transformation is not completed until a period ap- 

 parently considerably later. However, I believe this difference is 

 merely in appearance, lying in the fact that the nuclear membrane 

 is reconstructed much earlier in insect cells. 



At this stage the cells of Scolopendra enter upon a period re- 

 markable for the extraordinary changes which take place in their 



FIG. 6. X I >44 dia. Slightly later stage. The chromatin segments scattered 

 throughout entire nuclear space. 



FIG. 7. X 1)44 dia. Chromatin partly gathered about the accessory chromosome 

 to form the karyosphere. Remaining chromatin of the cell present in the form of 

 very diffuse segments. Spindle remains of last spermatogonial divisions still persist. 



structure. At first glance the most striking of these changes 

 seems to be the enormous increase in the size of the cells (Figs. 

 6, 7 and 8). This growth I have already described briefly in a 

 preliminary paper and shall have occasion to describe more in 

 detail in subsequent communications. In this connection it will 

 suffice to say that very often the diameter of the larger sperma- 



