ACCOUNT OF THE GERM-CELL CYCLE 41 
until, as shown in Fig. 7, the central part of the 
odcyte consists of homogeneous cytoplasm (cy), and 
the outer region of the cytoplasm is crowded with 
granules and spherical bodies of various sizes. 
Apparently the mitochondria lying near the periphery 
(Fig. 8, H) increase in size, gradually losing their 
affinity for the crystal violet stain and swelling up 
until they constitute the large yolk globules so 
numerous in the mature egg. All stages in the 
evolution of these bodies are illustrated at this time 
as represented in Fig. 8, H. In the meantime 
material is brought into the egg through the egg 
string from the nurse cells, thus probably adding 
several sorts of granules to the contents of the odcyte. 
The growth period in the male germ-cell cycle is 
not so striking as in the female, since many sperma- 
tozoa of small size are produced, whereas only 
comparatively few large eggs develop. An increase 
in the size of the ultimate spermatogonia may occur, 
however, but the multiplication and growth periods 
are not nearly so distinct as in the case of the odgonia. 
In testes which are composed of cysts of spermato- 
gonia there is evidence in some cases that all of the 
germ cells in a single cyst are descendants of a single 
spermatogonium. The proof for this seems certain 
in the potato beetle, where I have been able to 
follow the formation of the cysts by means of an 
uninterrupted series of stages (Hegner, 1914a). 
7. Maturation. Maturation or the ripening 
of the eggs and spermatozoa comprises a series of 
events which results in a reduction in the number 
