Physiological office of the senzen. — Al though these results of chemical analysis appear very important for the knowledge of the nature and quality of the semen, yet they afford but little assistance to an in vestigation respecting its znodus operandi in the process of fecundation. Indeed, it would almost seem that an answer to such an inquiry is farther off than ever, inasmuch as me now know that a peculiar substance of a specific quality exists, which me may indeed consider as the bearer of the fructifying prin ciple,—but that an effective spermatine does not exist. The truth is, " the how" of the fecundation is as far from our knowledge to day as it was thousands of years ago ; this process is still enveloped in what we feel in clined to consider " its sacred mystery." It would be different if we could prove that the spermatozoa really yielded the material found ation for the body of the embryo ; that they penetrated into the ovum, and were deve loped into the animal (which was the assump tion of Leuwenhoek, Andry, Gautier), or else, that they become metamorphosed into the central parts of the nervous system.
However, we are now convinced that all these assumptions are without any found ation. The import of the spermatozoa must be a very different one. But this is the very point of which we know nothing with any certainty.
Leaving these views, which require no spe cial refutation, to oblivion, the following two opinions on the nature of fecundation have taken a tolerable position in our physiology : —One of them consists in the opinion that the fructifying principle is lodged in the liquor seminis ; the other, that it is centred in the spermatozoa. Both, however, agree in this, that an actual material meeting, an immediate contact of semen and ova, is indispensable to effect feCundation. The doctrine of an Aura soninalis has long since, and most justly, been cast aside.
It was natural that the former of these two opinions (viz. that which sought the essentials of fecundation in the fluid and its mode of action) should have found its advocates at a period when the existence of the spermatozoa was hardly known, or when, at all events, they were supposed to be mere parasitic animal forms.
Indeed, this assumption is at first sight sup ported by arguments of a seductive nature. The liquor seminis, it was thought, comes into contact with the membranes of the ovum, and transudes them. It mixes itself with parts of the yolk, and enters with them into many chemical combinations, which fit them for a change in their capacity for organization, for the formation of cells, and for the developement of the embryo. This opinion did not, indeed, suffer at first from the recognition of the nor mal nature of the spermatozoa. It was in
deed possible, as Burdach thought, to find in this very circumstance a proof of the great organizability of the semen, of the ready mode of dispersing it, which such an operation upon the ovutn would ci priori require.
Even up to the present day this h3pothesis of the influence of the liquor seminis has not met with any direct refutation, although, as we shall see presently, it appears to us now, for many reasons, less admissible than it did to one of us formerly.* The presence of certain elementary structures in the seminal fluid cannot yet be connected with the part which they are intended to perform. It was indeed possible that the remarkable qualities of these structures had reference to the semi nal fluid alone ; that they, as it were, formed isolated, free, ciliated epithelia, and that they were intended, by means of their movement, to bring the liquor seminis into contact with the ovum ; or, as Valentin supposed, that the state of mixture of the semen, so readily dis turbed, was preserved in its integrity through their motions. The circumstance of meeting now and then with motionless spermatozoa is not in itself sufficient to refute this con jecture. For it might be said that in these cases such a provision might not be neces sary, or that the object sought might be gained in another way, and that the spermatozoa merely existed as morphological equivalents of the moveable seminal fibres, without a similar pltysiological importance.
The following fact, hem ever, appears to us of more real importance, viz. that a liquor se minis is positively not at all traceable in many, and especially not in many of the lower, ani mals, in worms, insects, &c. ; but that, on the contrary, the whole mass of the semen is formed by the spermatozoa alone. Another reason against the former assumption is this, that an action of the liquor seminis on the ova would be impossible in many cases,— where, for instance, the fecundation takes place in the water, and without any real act of copulation, the semen being ejected from the male animals, and then left to chance whether it comes in contact with the ova or not. • Such facts speak too powerfully in favour of a specific purport of the spermatozoa in the act of impregnation to allow us to venture to say a word in support of the older assumption. In addition to this, it must be granted that the spermatozoa in the male individuals are, in a morphological point of view, the representatives of the female generative products the ova ; and that, as explained in the commencement of our article, we are enabled to pronounce the presence of a particularly large quantity of liquor seminis as a fact of subordinate significance in a his tolo,rical point of view.