Fruits of Philosophy: A Treatise on the Population Question

by Charles Knowlton

Sixth. "Harvey and DeGraaf dissected animals at almost every period after coition for the express purpose of discovering the semen, but were never able to detect the smallest vestige of it in the uterus in any one instance."*

* Dewees' Essay on Superfoetation.—Author's note.

Aware of the insurmountable objection to this view of the manner in which the semen reaches the ovary, it has been supposed by some physiologists that the semen is absorbed from the vagina into the great circulating system, where it is mixed, of course, with the blood, and goes the whole round of the circulation subject to the influence of those causes which produce great changes in the latter fluid.

To this hypothesis it may be objected, that while there is no direct evidence in support of it, it is exceedingly unreasonable, inasmuch as we can scarcely believe that the semen can go the whole round of circulation, and then find its way to the ovary in such a pure unaltered state as the experiments of Spallanzani prove it must be in, that it may impregnate.

A third set of theorists have maintained that an imperceptible something, which they have called aura seminalis, passes from the semen lodged in the vagina to the ovary, and excites those actions which are essential to the development of an ovum. Others, again, have told us that it is all done by sympathy. That neither the semen nor any volatile part of it finds its way to the ovary; but that the semen excites the parts with which it is in contact in a peculiar manner, and by the law of animal economy, termed sympathy, or consent of parts, a peculiar action commences in the ovary, by which an ovum is developed.

To both these conjectures it may be objected that they have no other foundation but the supposed necessity of adopting them, to account for the effect of impregnation; and, further, they "make no provision for the formation of mules; for the peculiarities of, and likeness to, parents, and for the propagation of predisposition to disease, from parent to child; for the production of mulattoes," etc.

A fifth, and to me far more satisfactory view of the subject than any other, is that advanced by our distinguished countryman, Dr. Dewees, of Philadelphia. It appears to harmonize with all known facts relating to the conception and something from analogy may also be drawn in its favor. It is this, that there is a set of absorbent vessels, leading directly from the inner surface of the labia externa and the vagina, to the ovaries, the whole office of which vessels is to absorb the semen and convey it to the ovaries.* I do not know that these vessels have yet been fully discovered, but in a note on the sixteenth page of his "Essays on Various Subjects," the doctor says: "The existence of these vessels is now rendered almost certain, as Dr. Gartner, of Copenhagen, has discovered a duct leading from the ovary to the vagina."

* This view is not held at the present day. The commonly
received doctrine now is that the seminal fluid enters the
uterus, whether during the intercourse or after it, and
passes along the Fallopian tubes to the ovaries; and that
fecundation takes place at some point of this course, most
frequently in the tubes, but also at times in the ovary
itself, or even, perhaps, in the uterus. It is essentially
necessary for fecundation that the spermatozoa should come
into actual contact with the ovum. "That the spermatozoa
make their way toward the ovarium, and fecundate the ovum
either before it entirely quits the ovisac or very shortly
afterward," says Dr. Carpenter, "appears to be the general
rule in regard to the Mammalia; and their power of movement
must obviously be both vigorous and long continued to enable
them to traverse so great an extent of mucous membrane,
especially when it is remembered that they ascend in
opposition to the direction of the ciliary movement of the
epithelial cells and to the downward peristaltic action of
the Fallopian tubes. * * * There can be no doubt that it is
the contact of the spermatozoa with the ovum, and in the
changes which occur as the immediate consequence of that
contact, that the act of fecundation essentially consists."
—"Principles of Human Physiology," 8th ed., p. 961,1876.—G.R.

Another question of considerable moment relating to generation is from which parent are the first rudiments of the foetus derived.

The earliest hypothesis with which we are acquainted, and which has received the support of some of the most eminent of the moderns, ascribes the original formation of the foetus to the combination of particles of matter derived from each of the parents. This hypothesis naturally presents itself to the mind as the obvious method of explaining the necessity for the cooperation of the two sexes, and the resemblance in external form, and even in mind and character, which the offspring often bears to the male parent. "The principal objections," says Bostock, "to his hypothesis, independent of the want of any direct proof of a female seminal fluid, are of two descriptions, those which depend upon the supposed impossibility of unorganized matter forming an organized being, and those which are derived from observations and experiments of Haller and Spallanzani, which they brought forward in support of their theory of pre-existent germs."