THE OVARIAN EGG. 275 
tain types; so that the individuals are uniformly 
hermaphrodites, — yet I firmly believe that this 
numerical distribution, however unequal it may 
seem to us, is not without its ordained accuracy 
and balance. He who has assigned its place to 
every leaf in the thickest forest, according to an 
arithmetical lay which prescribes to each its al- 
lotted share of room on the branch where it grows, 
will not have distributed animal life with less 
care and regularity. 
Although reproduction by eggs is common to 
all animals, it is only one among several modes 
of multiplication. We have seen that certain 
animals, besides the ordinary process of genera- 
tion, also increase their numbers naturally and 
constantly by self-division, so that out of one in- 
dividual many individuals may arise by a natural 
breaking up of the whole body into distinct sur- 
viving parts. This process of normal self-division 
may take place at all periods of life: it may form 
an early phase of metamorphosis, as in the Hy- 
droid of our common Aurelia, described in the 
last article; or it may even take place before the 
young is formed in the egg. In such a case, the 
ege its@lf divides into a number of portions, — 
two, four, eight, or even twelve and sixteen in- 
dividuals being normally developed from every 
egg, in consequence of this singular process of 
segmentation of the yolk, which takes place, 
