From the first exertion of philosophical investigation. it is reasonable to suppose that the source and means of our existence must have employed the reflections of those who were capable of penetrating in their inquiries beyond the narrow sphere which surrounded them; and, at different eras, it was believed that both the male and female contributed to the production; that the male was the only agent, while the female afforded support and nourishment; or that the foetus was produced and

4U 2 nourished by the female, and animated only in the moment of generation. We shall speak of each opinion, and its authors, very shortly, in their order.

The first and most obvious opinion was that of Hippocrates and Harvey. It is indeed highly reasonable, and supported by every appearance: though the more modern systems of Haller, Bonnet, and Spalanzani, must, in some measure, modify and extend this theory, it will not be easy wholly to deny it. The discovery, however, of animalcules in semine masculino, for a time directed the views of physiologists to the second opinion; and Leuenhoeck, its author, eagerly supposed that he could discover among these embryos of each sex. Animalcules, however, are found in every fluid; and these appear only after some time, when a degree of putrefaction has probably taken place. More modern discoveries, also, respecting the changes progressively occurring in incubation, have wholly destroyed this system. Buffon, in his fanciful doctrine of the molecules organiques, has improved on this theory, and apparently attributes the production of the foetus to the union of animated particles from each parent. The whole is embellished by his fancy, and adorned by his eloquence; but we can scarcely admit of their influence, except in more remote arrangements; and indeed the existence of these molecules must be considered rather as a probable idea than a fact, which admits of proof or application. The discoveries of Haller and of Bonnet respecting the origin and independent life of the chick, in ovo, have greatly altered the views of physiologists on this subject: these have been assisted by Dr. Hunter's observations on the human gravid uterus atvarious periods of impregnation, and the result is the third of the opinions stated, which as the more recent and fashionable, we shall proceed to explain, with its various modifications suggested by different authors, and by the facts themselves.

According to this system, the foetus pre-exists in the ovarium of the female; and in the moment of impregnation is detached from it. A vesicle remains (the corpus luteum), from whence it was apparently separated, a cavity peculiarly vascular, as is always found when any loss is to be supplied. To this is added, that when twins are contained in the womb, two of these vesicles are found. The ovaria are two spheroidal flattened bodies, inclosed between the folds of the broad ligaments, by which the uterus is, in part, suspended. They have no immediate connection with the uterus; but near them the extremity of a tube, which opens on either side into that organ, hangs with loosfe fimbriae in the cavity of the abdomen. It is supposed, then, that in the venereal orgasm these extremities arc erected, that they grasp the ovarium, and receive the ovum. This would appear fanciful and hypothetical, but that a perfect foetus has been found in the ovarium, in these tubes, and even been discovered in the cavity of the abdomen, having apparently eluded the grasp of the fimbriae. In neither case could the fetus have ascended from the uterus, for whatever difficulty attends the hypothesis now to be explained, will act with equal force against this idea; and to it must be added, that on the latter supposition the embryo must depart from its nidus, where it is to be supported and nourished; on the former he approaches to it.

We may conclude, then, that the foetus really preexists in the ovarium; but the question remains, how it is animated. The access of the male semen is known to be necessary; but the difficulty which attends the passage of the foetus into the uterus equally militates against the progress of the semen into the ovarium. It has been eluded by Harvey, who supposes a seminal aura to reach the ovary; and by a Mr. Johnston, who suspects that the semen is absorbed, and carried to this organ through the medium of the circulation. The latter, for many reasons improper to be detailed in a popular work, is not probable; and the aura, when speaking of the foetus, we have shown to be a vague and unsupported medium. In short, every view of the subject seems to show that the semen has a ready access to the embryo. In the same moment that the one is detached from the ovary and conveyed to the uterus, the other may reach that organ. But the foetus when in the Fallopian tubes, or the abdomen, is animated, so that it is more probable, that by some action of the uterus and its tubes the semen is conveyed to the ovarium; and every fact shows that the muscular fibres of the uterus are at that moment most highly excited. It is certain, that for the purpose of impregnation the semen must reach the cavity of the womb.

Here then induction ends; and difficulties begin. From this view it may appear obvious, that generation is only the animation of a pre-existing germ; and that as we have shown the foetus to be an independent being, at least dependent only on the mother for a supply of fluids, we have no difficulty in accounting for its growth, and the successive evolution of its different organs. Such, however, would be the conclusion of a shallow, uninformed physiologist. The union of a male and female of different species, even in the vegetable kingdom, is followed by an hybrid production, partaking the properties of both. The mule, the offspring of a horse and an ass, is a familiar example. In a large family, some of the children will partake the form, the temper, the diseases of the father; others of the mother. This cannot be owing merely to the means of excitement, much less to the small portion of nutriment which the semen can afford, supposing it a nutritious fluid, an idea anxiously supported. Bonnet's mechanical system of a net-work, the meshes of which the semen fills, thus modifying the form, is still less tenable; nor can we escape from the opinion first stated, that the male as well as the female contributes to the formation of the future offspring. The primordial embryo is undoubtedly in the female; but the"man stamps an image of himself," the"world's first wonder," either by an union of principles, or a modification of those which pre-existed, in a manner which will probably never be explained.

We have thus given, in a few words, the substance of numerous extensive disquisitions, endeavouring to distinguish facts from hypotheses. We shall be gratified if it should appear that we have explained the subject comprehensively, so far as it will admit of explanation; more so, if we shall be found to have avoided the pruriencies, which, under the veil of science, are so often indulged, and whose only purpose is to gratify sensuality. See Mailer's Physiology, lecture 33; also the article Conceptio in this work.