THE PAHDOGENETIC FLY, MIASTOR — 57 
The nuclei present at the four-cell stage occupy 
rather definite positions and may be numbered for 
convenience by the Roman numerals I, II, III, 
and IV, as indicated in Fig. 15. The division from 
the four- to the eight-cell stage is a very important 
one, since it is at this time that the primordial 
Fic. 16.— Miastor metraloas. Stages in the chromatin-diminution 
process. (From Kahle, 1908.) 
germ cell is established. Each of the four nuclei 
divides by mitosis, but nuclei I, I, and III undergo 
a chromatin-diminution process during which a 
large part of their chromatin remains in the cyto- 
plasm when the daughter nuclei reform. The details 
of such a process are indicated in Fig. 16. Nucleus 
IV, on the other hand, divides as usual (Fig. 15) and 
each daughter nucleus receives one-half of its chroma- 
tin. One of these daughter nuclei becomes embedded 
in that peculiar mass of cytoplasm at the posterior 
