with its seven twin portions; so
that in the end, instead of a single embryo growing out of this yolk,
we have eight embryos arising from a single yolk, each one of which
undergoes a series of developments similar in all respects to that by
which a single embryo is formed from each egg in other animals. We have
other Naticas in which the normal number is twelve, others again in
which no less than sixteen individuals arise from one yolk. But this
process of segmentation, though in these animals it leads to such a
multiplication of individuals, is exactly the same as that discovered
by K.E. von Baer in the egg of the Frog, and described and figured by
Professor Bischof in the egg of the Rabbit, the Dog, the Guinea-Pig,
and the Deer, while other embryologists have traced the same process in
Birds, Reptiles, and Fishes, as well as in a variety of Articulates,
Mollusks, and Radiates.

Multiplication by division occurs also normally in adult animals that
have completed their growth. This is especially frequent among Worms;
and strange to say, there are species in this Class which never lay eggs
before they have already multiplied themselves by self-division.

Another mode of increase is that by budding, as in the Corals and many
other Radiates. The most common instance of budding we do not, however,
generally associate with this mode of multiplication in the Animal
Kingdom, because we are so little accustomed to compare and generalize
upon phenomena that we do not see to be directly connected with one
another. I allude here to the budding of trees, which year after year
enlarge by the addition of new individuals arising from buds. I trust
that the usual acceptation of the word _individual_, used in science
simply to designate singleness of existence, will not obscure a correct
appreciation of the true relation of buds to their parents and to the
beings arising from them. These buds have the same organic significance,
whether they drop from the parent stock to become distinct individuals
in the common acceptation of the term, or remain connected with
the parent stock, as in Corals and in trees, thus forming growing
communities of combined individuals. Nor will it matter much in
connection with the subject under discussion, whether these buds start
from the surface of an animal or sprout in its interior, to be cast off
in due time. Neither is the inequality of buds, varying more or less
among themselves, any sound reason for