286 THE OVARIAN EGG. ~ 
the senses, between the organs of instinct and 
sensation and those of mere animal functions. 
At that stage of its existence, however, when 
the egg consists of an outer sac, an inner sac, 
and a dot, its resemblance to a cell is unmis- 
takable; and, in fact, an egg, when forming, is 
nothing but a single cell. This comparison is 
important, because there are both animals and 
plants which, during their whole existence, con- 
sist of a single organic ccll, while others are 
made up of countless millions of such cells. Be- 
tween these two extremes we have all degrees, 
from the innumerable cells that build up the 
body of the highest Vertebrate to the single- 
celled Worm, and from the myriad cells of the 
Oak to the single-celled Alga. 
But while we recognize the identity of cell- 
structure and egg-structure at this point in the 
history of the egg, we must not forget the great 
distinction between them, — namely, that while 
the cells remain component parts of the whole 
body, the egg separates itself, and assumes a dis- 
tinct individual existence. Even now, while still 
microscopically small, its individuality begins. 
Other substances collect around it, are absorbed 
into it, nourish it, serve it. Every being is a 
centre about which many other things cluster 
and converge, and which has the power to assiml- 
late to itsclf the necessary elements of its life. 
