1904.] NATURAL SCIENCES OF PHILADELPHIA. dol 
above and the sperm, which is the smaller, below. The clear granular 
protoplasm of the egg together with the sphere material surrounds both 
nuclei. The upper surface of the egg has resumed its former rounded 
outline, pushing the polar bodies farther outward. Their connection 
with the egg does not appear to be a very intimate one for they do not, 
in most cases, maintain at a later period any fixed relation to the poles 
of the egg and so are of little value in orientation, though they are 
often found in the apical region. 
UNSEGMENTED Eaa. 
The unsegmented egg of Fiona averages in diameter 80 micra with 
polar axis slightly less. The two polar bodies lie at the animal pole. 
Though the ovum is rather densely yolk-ladened, the yolk globules are 
of such small size that in future cleavages they tend to become more 
equally distributed among the resulting blastomeres than is the case 
with eggs containing yolk in larger spheres. The yolk which en- 
croaches upon the more protoplasmic environs of the nucleus consists 
of smaller globules, but otherwise its distribution throughout seems 
quite equal. 
The universal distribution of yolk to all the cells of the segmenting 
egg of Fiona is probably to be correlated with the smaller size of the 
individual yolk globules. It is safe to infer that each yolk body in an 
egg, whether it be small or large, is surrounded by a thin layer of 
protoplasm. In eggs containing a relatively larger number of yolk 
globules or, in other words, where they are small in size, a greater 
amount of cytoplasm will be distributed throughout the egg, when 
compared with that aggregated around the nucleus, than is the case 
when the single aggregations of yolk are large. When this is the case 
and division occurs the whole mass will be more influenced by nuclear 
and cytoplasmic divisional activity than when the cytoplasmic con- 
stituents are more definitely separated from the yolk. Just what this 
activity is we do not know, but a comparative study of eggs showing 
large macromeres with those like Fiona, in which cleavage is more 
equal, will, I think, show that in the former case the individual yolk 
masses are much larger than in the latter, thus allowing for greater 
cytoplasmic influence where more finely divided yolk is found. The 
more equal division of cells naturally results in a wider spread of yolk 
through the developing organism, and it might also be added, as a corol- 
lary to this, that the absorption of more finely divided yolk is doubtless 
much more readily accomplished than where large globules are found, 
thus rendering it possible that such a wide distribution should oceur in 
cells not alimentary in function. 
