GERM CELLS OF COELENTERATES 399 
conclude that the nucleolus actually stands in some causal rela- 
tion to these changes. 
Now plainly the whole egg during the period of growth is in 
a most active state of metabolism. In addition to the ordinary 
functions which it has to conduct in order to remain alive there 
is the further task of preparation for the cleavage period which is 
to come, in which it will not receive food from the outside. This 
rests principally in the storing of food as reserve for that period 
of activity. Even if we assume that the food which enters the 
egg from the enteric cavity has already been digested, there is the 
necessity for a great amount of it to be synthesized into the 
stored products needed later, and also a lot to be assimilated and 
used for the present needs of growth. Perhaps this is the most 
strenuous period of activity of any single cell in the life story of 
the cells of the body. Apparently, then, the nucleolus stands in 
some rather close relation to this activity of the egg cell during 
the active growth period. If not actually taking part in the 
transformation of the food itself it is closely related in some other 
way. ‘The odd shapes assumed by the nucleolus may, therefore, 
be for the purpose of securing as much exposure of surface as 
possible. The nucleolus certainly aids in transforming some of 
the material, since this body alone is not sufficient to account for 
the increase in substances within and without the nucleus. 
The origin of the nucleolus in the egg cell was not definitely 
determined, for in the earliest recognizable egg the nucleolus was 
already present. But the behavior is sufficiently clear. In the 
young eggs (figs. 2, 3, 4) the nucleolus is very small, smaller 
even than the nucleolus of the neighboring ectoderm and entoderm 
cells, though the nucleus is larger in the egg cell. But coincident 
with the disappearance of the spireme in the young egg cell, which 
takes place very quickly, the nucleolus enlarges considerably, 
even before the body of the egg increases. The nucleolus arises 
then, within the nucleus and evidently from the chromatic spireme 
(at least in part), but all of the chromatin does not enter the 
nucleolus, for in addition and at the same time a chromatic 
reticulum is formed in the nucleus; also the staining reactions 
show that the nucleolus contains a lot of non-chromatic matter. 
