The word ovum is defined as: “An egg in a broad biological sense;
and the proper product of an ovary; the female germ or seed, which,
when fertilized by the male sperm, is capable of developing into
an individual like the parents.… An ovum consists of a quantity of
protoplasm or cell-substance called the vitellus or yolk inclosed in
a cell-wall or vitelline membrane, and provided with a nucleus and
nucleolus.” (Cent. Dic. 5, p. 4212.)
“The ovum (egg) is extremely small,” says Haeckel, “being a tiny round
vesicle about 1/120th of an inch in diameter; it can be seen under
favorable circumstances with the naked eye as a tiny particle, but is
otherwise quite invisible. This particle is formed in the ovary inside
a much larger globule, which takes the name of the Graäfian follicle,
from its discoverer, Graäf, and [which] had been previously regarded as
the true ovum.” (Evolution of Man, chap. 3, pp. 16-17.)
“Man is developed,” says Darwin, “from an ovule (little egg) about the
1/125th of an inch in diameter, which differs in no respect from the
ovules of other animals.” (Descent of Man, chap. 1, p. 9.)
“In man,” says Romanes, “as in most mammals, it (the ovum or egg-cell)
is about 1/120th of an inch in diameter.” (Romanes, _Darwin and After
Darwin_, 1, p. 120.)
Supposing the human egg to be 1/120th of an inch in diameter and an
ordinary pin’s head to be 1/16th of an inch in diameter, which is about
its size, the egg would be about 1/7th of the size of a pin’s head.
Haeckel says: “In the lower vertebrates the formation of ova (eggs) in
the germ-epithelium of the ovary continues throughout life; but in the
higher animals it is restricted to the earlier stages, or even to the
period of embryonic development.
“In man it seems to cease in the first year; in the second year we find
no new-formed ova (eggs) or chains of ova (Pfluger’s tubes.) However,
the number of ova (eggs) in the two ovaries is very large in the young
girl. There are calculated to be 72,000 in the sexually mature maiden.”
(_Evolution of Man_, chap. 29, p. 347.)
“The human ovum,” says Haeckel, “whether fertilized, or not, cannot be
distinguished from that of most other mammals. It is nearly the same
everywhere, in form, size, and composition. When it is fully formed,
it has a diameter of (on an average) about 1/120th of an inch. When
the mammal ovum (egg) has been carefully isolated and held against the
light on a glass-plate, it may be seen as a fine point even with the
naked eye. The ova (eggs) of most of the higher animals are about the
same size. The diameter of the ovum (egg) is almost always between
1/250th and 1/125th of an inch. It has always the same globular shape;
the same characteristic membrane; the same transparent germinal vesicle
with its dark germinal spot.
“Even when we use the most powerful microscope,” he continues, “with
its highest power, we can detect no material difference between the
ova (eggs) of man, the ape, dog, and so on. I do not mean to say that
there are no differences between the ova (eggs) of these different
mammals. On the contrary, we are bound to assume that there are such
[differences] at least as regards chemical composition. Even the ova
(eggs) of different men must differ from each other; otherwise we
should not have a different individual from each ovum (egg). It is
true that our crude and imperfect apparatus cannot detect these subtle
individual differences which are probably in the molecular (atomic)
structure.”--(_Evolution of Man_, _chap. 6_, p. 44.)