294 GERM-CELL CYCLE IN ANIMALS 
eight nuclei. in the egg. As determined by Kahle 
(1908) and confirmed by the writer (Hegner, 1912, 
1914a), this primordial germ cell gives rise to sixty- 
four odgonia and to no other cells. This is the nearest 
approach to a complete morphological continuity 
of the germ cells that has yet been described, and 
since this primordial germ cell must contain the germ- 
plasm of the succeeding generation, the condition 
in this fly is really comparable to that of the hypo- 
thetical case cited above, only in Miastor the cell 
set aside for reproductive purposes is much less than 
one-half of the egg, the somatic part of the egg being 
not a single cell, but a syncytium containing seven 
nuclei. 
We may therefore look for the germ-plasm of 
Muastor in the primordial germ cell. So far as we 
know there are only two sorts of materials in this 
cell, that contained in the nucleus, and the darkly 
staining part of the egg which becomes recognizable 
just before maturation occurs, is situated at the pos- 
terior pole, and has been termed the pole-plasm 
(Fig. 13). If the primordial germ-cell multiplies by 
simple division and if there is an equal distribution 
of the contents at every mitosis, then the sixty- 
four odgonia must each possess one sixty-fourth of 
both the nucleus and the pole-plasm of the primordial 
gverm cell plus any materials that have been added 
during the period of multiplication. An enormous 
enlargement occurs during the growth period both of 
the nucleus and of the cell. The pole-plasm cannot 
be recognized at this time, but again becomes 
