IV. The myth of the scatulation of the soul (the theory of Leibnitz which we have given above).
V. The myth of the division of the soul (the theory of Rudolph Wagner [1855] and of other physiologists).—In the act of procreation a portion is detached from both the (immaterial) souls of the parents; the maternal contribution passes in the ovum, the paternal in the spermatozoa; when these two germinal cells coalesce, the two psychic fragments that accompany them also combine to form a new (immaterial) soul.
Although the poetic fancies we have mentioned as to the origin of the individual human soul are still widely accepted, their purely mythological character is now firmly established. The deeply interesting and remarkable research which has been made in the course of the last twenty-five years into the more minute processes of the impregnation and germination of the ovum has made it clear that these mysterious phenomena belong entirely to the province of cellular physiology (cf. [p. 48]). Both the female element, the ovum, and the male fertilizing body, the sperma or spermatozoa, are simple cells. These living cells possess a certain sum of physiological properties to which we give the title of the “cell-soul,” just as we do in the permanently unicellular protist (see [p. 48]). Both germinal cells have the faculty of movement and sensation. The young ovum, or egg-cell, moves after the manner of an amœba; the minute spermatozoa, of which there are millions in every drop of the seminal fluid, are ciliated cells, and swim about as freely in the sperm, by means of their lashes or cilia, as the ordinary ciliated infusoria (the flagellata).
When the two cells meet as a result of copulation, or when they are brought into contact through artificial fertilization (in the fishes, for instance), they attract each other and become firmly attached. The main cause of this cellular attraction is a chemical sensitive action of the protoplasm, allied to smell or taste, which we call “erotic chemicotropism”; it may also be correctly (both in the chemical and the romantic sense) termed “cellular affinity” or “sexual cell-love.” A number of the ciliated cells in the sperm swim rapidly towards the stationary egg-cell and seek to penetrate into it. As Hertwig showed in 1875, as a rule only one of the suitors is fortunate enough to reach the desired goal. As soon as this favored spermatozoon has pierced into the body of the ovum with its head (the nucleus of the cell), a thin mucous layer is detached from the ovum which prevents the further entrance of spermatozoa. The formation of this protective membrane was only prevented when Hertwig kept the ovum stiff with cold by lowering the temperature, or benumbed it with narcotics (chloroform, morphia, nicotine, etc.); then there was “super-impregnation” or “poly-spermy”—a number of sperm-threads pierced into the body of the unconscious ovum. This remarkable fact proved that there is a low degree of “cellular instinct” (or, at least, of specific, lively sensation) in the sexual cells just as effectively as do the important phenomena that immediately follow in their interior. Both nuclei—that of the ovum and of the spermatozoon—attract each other, approach, and, on contact, completely fuse together. Thus from the impregnated ovum arises the important new cell which we call the “stem-cell” (cytula), from the repeated segmentation of which the whole polycellular organism is evolved.
The psychological information which is afforded by these remarkable facts of impregnation, which have only been properly observed during the last twenty-five years, is supremely important; its vast significance has hitherto been very far from appreciated. We shall condense the main conclusions of research in the following five theses:
I. Each human individual, like every other higher animal, is a single simple cell at the commencement of his existence.
II. This “stem-cell” (cytula) is formed in the same manner in all cases—that is, by the blending or copulation of two separate cells of diverse origin, the female ovum and the male spermatozoon.
III. Each of these sexual cells has its own “cell-soul”—that is, each is distinguished by a peculiar form of sensation and movement.
IV. At the moment of conception or impregnation, not only the protoplasm and the nuclei of the two sexual cells coalesce, but also their “cell-souls”; in other words, the potential energies which are latent in both, and inseparable from the matter of the protoplasm, unite for the formation of a new potential energy, the “germ-soul” of the newly constructed stem-cell.