66 GERM-CELL CYCLE IN ANIMALS 
provided with a group of about twenty-four meso- 
derm cells which form a syncytium at the anterior 
end and may be called nurse cells (Fig. 25, n.c), since 
they furnish food material to the odcyte. Another 
group of mesoderm cells forms a cellular layer about 
the odcyte and nurse cells, and thus constitutes a 
follicular epithelium. At this stage the odcytes 
break away from the ovary and become distributed 
in various parts of the body of the mother-larva. 
Several facts regarding the germ-cell cycle of 
Miastor deserve special emphasis: (1) There is 
no stage in the entire keimbahn when the germ cells 
cannot be distinguished without the least difficulty ; 
(2) the number of odgonial divisions has been defi- 
nitely established, and so it is no longer necessary to 
make the general statement that the germ cells 
pass through n divisions during the period of multi- 
plication, since here n is undoubtedly six; (3) the 
descendants of the primordial germ cell are only 
germ cells, z.e., the primordial germ cell does not 
give rise to both odgonia and nurse cells as seems to 
be the case in most other insects; (4) chromatin- 
diminution processes take place during the mitotic 
divisions of the nuclei from the four- to the eight- 
cell stage and form the eight- to the fifteen-cell 
stage of such a nature that all of the cells in the 
embryo finally are deprived of part of their chromatin 
with the exception of the primordial germ cell which 
retains the complete amount of this substance; 
(5) the primordial germ cell is established at the 
eight-cell stage and is the first complete cell formed in 
