ve not only parts, but movements in
common.

The existence of free gemmules is a gratuitous assumption, yet can hardly
be considered as very improbable, seeing that cells have the power of
multiplication through the self-division of their contents. Gemmules differ
from true ovules or buds inasmuch as they are supposed to be capable of
multiplication in their undeveloped state. No one probably will object to
this capacity as improbable. The blastema within the egg has been known to
divide and give birth to two embryos; and Thuret[904] has seen the zoospore
of an alga divide itself, and both halves germinate. An atom of small-pox
matter, so minute as to be borne by the wind, must multiply itself many
thousand-fold in a person thus inoculated.[905] It has recently been
ascertained[906] that a minute portion of the mucous discharge from an
animal affected with rinderpest, if placed in the blood of a healthy ox,
increases so fast that in a short space of time "the whole mass of blood,
weighing many pounds, is infected, and every small particle of that blood
contains enough poison to give, within less than forty-eight hours, the
disease to another animal."

The retention of free and undeveloped gemmules in the same body from early
youth to old age may appear improbable, but we should remember how long
seeds lie dormant in the earth and buds in the bark of a tree. Their
transmission from generation to generation may appear still more
improbable; but here again we should remember that many rudimentary and
useless organs are transmitted and have been transmitted during an
indefinite number of generations. We shall presently see how well the
long-continued transmission of undeveloped gemmules explains many facts.

As each unit, or group of similar units throughout the body, casts off its
gemmules, and as all are contained within the smallest egg or seed, and
within each spermatozoon or pollen-grain, their number and minuteness must
be something {379} inconceivable. I shall hereafter recur to this
objection, which at first appears so formidable; but it may here be
remarked that a cod-fish has been found to produce 4,872,000 eggs, a single
Ascaris about 64,000,000 eggs, and a single Orchidaceous plant probably as
many million seeds.[907] In these several cases, the spermatozoa and
pollen-grains must exist in considerably larger numbers. Now, when we have
to deal with numbers such as these, which the human intellect cannot grasp,