A word, then, upon this matter of the fusion of the two parent cells in one. Here, again, two very remarkable things appear. One refers to the equality of the sexes; the other refers to the onesidedness (or deficiency or imperfection) which seems to be the characteristic and the motive power of the phenomenon of sex.
With regard to the first point, we saw that among the Protozoa conjugation occurs for the most part between two individual cells which are alike in size and (to all appearance) alike in constitution; and this conjugation leads to reproduction. But when among the higher forms sex begins to show, the conjugating cells—sperm-cell and germ-cell—are generally unlike in size, and often in the higher animals extremely unlike—as in the human spermatozoon and ovum, of which the latter is a thousand times the volume of the former;[10] and this has sometimes led, as remarked before, to an exaggerated view of the preponderant importance of one sex. But the curious fact seems to be that when the spermatozoon of the human or higher animal penetrates the ovum, there is a preliminary period before its nucleus actually combines with the nucleus of the ovum, during which the nucleus rapidly absorbs nourishment from the surrounding protoplasm, and grows—grows till it becomes of exactly the same size as the nucleus of the ovum. The situation then is that there are two nuclei of the same size and both charged with chromatin of the same general character, in close proximity, and waiting to fuse with each other.
The product of that fusion is a new being; and as far as can at present apparently be observed, the parts played by the two sexes in the process are quite equal. There may be difference of function but there is no inequality. “Both male and female cells,” says Professor Rolleston,[11] “prepare themselves for conjugation long before it takes place, and neither of them can be said to be a more active agent in fertilization than the other. Not ‘fertilization’ but ‘fusion’ is the keyword of the process. The mystical conception, as old as Plato, of the male and female as representing respectively the two halves of a complete being, turns out to be no poetic metaphor. As regards the essential features of reproduction, it is a literal fact.”
The second remarkable point has to do with the onesidedness of sexual conjugation, and the complementary nature of the exchange involved. This is truly noteworthy and interesting. It is evident that if the sperm-cell and germ-cell simply coalesced, containing each the amount of chromatin characteristic of the species—say sixteen chromosomes in the case of the human being—the result would be a cell with double the proper amount, say thirty-two chromosomes, i.e. an amount belonging to another species. “What happens is that each of the reproductive cells, male and female, prepares itself for conjugation by getting rid of half its chromosomes. Two divisions of the nucleus take place, not as in the ordinary fashion of cell-division, when the chromosomes split longitudinally, but in such a way that, in each division, four of the sixteen chromosomes (making eight in all) are bodily expelled from the nucleus and from the cell, when they either perish, or, in some cases, appear to help in forming an envelope of nutritive matter round the germ-cell. These divisions are called ‘maturation divisions,’ and until they are accomplished fecundation is impossible.”[12] Thus the two nuclei, having each their number of chromosomes reduced to half the normal number (in this case to eight), are now ready to coalesce and so form a new cell with the proper number belonging to the species (i.e. sixteen). This cell is the commencement of the new being, and, as already described, it divides and re-divides, and the innumerable cells so formed differentiate themselves into different tissues, until the whole animal is built up.
Says Professor E. B. Wilson:—“The one fact of maturation that stands out with perfect clearness and certainty amid all the controversies surrounding it, is a reduction of the number of chromosomes in the ultimate germ [and sperm] cells[13] to one half the number characteristic of the somatic cells. It is equally clear that this reduction is a preparation of the germ [and sperm] cells for their subsequent union, and a means by which the number of chromosomes is held constant in the species.”[14]
This extrusion or expulsion by each of the conjugating cells of half its constituent elements is certainly very strange.[15] And it seems strangely deliberate.[16] Various theories have been formed on the subject, but at present there is apparently no satisfactory conclusion as to what exactly takes place. Some think that in the one case certain male elements are expelled, and in the other case certain female elements; and anyhow it seems probable that a complementary action sets in, by which each prepares itself to supply a different class of elements from the other, thus rendering the conjunction more effectual. Plato has been already quoted with regard to male and female being only the two halves of a complete original being. He also says (in the speech of Socrates in the Banquet) that the mother of Love was Poverty, and that Love “possesses thus far his mother’s nature that he is ever the companion of Want.” And it would appear that in the most primitive grades of life the same is true, and that two cells combine or coalesce in order to mutually supply some want or deficiency.
Anyhow, in the process just described two points stand out pretty clear: first, the exact quality of the number of chromosomes contributed by sperm-cell and germ-cell to the fertilized ovum—which seems to indicate that the descendant being has an equal heredity from each parent[17]—though of course it does not follow that both heredities become equally prominent or manifest in the descendant body; and secondly, that the same is true of all the cells in this new body—that they each contain the potentialities of the joint cell from which they sprang, and therefore the potentialities of both parents.
These amazing conclusions concerning the origins of life and reproduction—here, of course, very briefly and imperfectly presented—cannot but give us pause. Contemplating the evolutions and affinities of these infinitely numerous but infinitely small organisms which build up our visible selves, and the strange intelligence which seems to pervade their movements, the mind reels—somewhat as it does in contemplating the evolutions and affinities of the unimaginable stars.[18] We seem, certainly, to trace the same laws or operations in these minutest regions as we trace in our own corporeal and mental relations. Cells attract each other just as human beings do; and the attraction seems to depend, to a certain degree, on difference. The male spermatozoon seeks the female ovum, just as the male animal, as a rule, seeks and pursues the female. Primitive cells divide and redivide and differentiate themselves, building up the animal body, just in the same way as primitive thoughts and emotions divide and redivide and differentiate themselves, building up the human mind. But though we thus see processes with which we are familiar repeated in infinitesimal miniature, we seem to be no nearer than before to any ‘explanation’ of them, and we seem to see no promise of any explanation. We merely obtain a larger perspective, and a suggestion that the universal order is of the same character throughout—with a suspicion perhaps that the explanation of these processes does not lie in any concatenation of the things themselves, but in some other plane of being of which these concatenations are an allegory or symbolic expression. In portions of the following chapters I shall trace more in detail the resemblance or parallelism between these processes among the Protozoa and some of our own experiences in the great matters of Life and Love and Death.[19]
CHAPTER III
LOVE AS AN ART