Sec. 16. Germ-Cell, Stem-Cell or Fertilized Ovum
The fertilized ovum is variously called, “germ-cell,” “stem-cell,” “first segmentation sphere,” “parent-cell,” “impregnated ovum,” “fertilized egg cell,” and other names of like import, all these phrases meaning the same thing.
Under the head, “Conception,” Haeckel says, among other things:
“The process of fertilization by sexual conception consists, therefore, essentially, in the coälescence and fusing together of two different cells. The lively spermatozoön travels toward the ovum by its serpentine movements and bores its way into the female cell. The nuclei of both sexual cells attracted by a certain affinity approach each other and melt into one.”—(Haeckel, Ev. Man, p. 53.)
How do they acquire this “affinity?” How do they know each other? Have they intellect, memory and will? Are they not driven toward each other by a supernatural, psychic force?
Continuing he says:
“The fertilized cell is quite another thing from the unfertilized cell. For if we must regard the spermia [spermatozoä] as real cells, no less than the ova, and the process of conception as the coälescence of the two we must consider the resultant cell as a quite new and independent organism. It bears in the cell and nuclear matter of the penetrating spermatozoön a part of the father’s body, and in the protoplasm of the ovum a part of the mother’s body. This is clear from the fact that the child inherits many features from both parents. It inherits from the father by means of the spermatozoön and from the mother by means of the ovum. The actual blending of the two cells produces a third cell, which is the germ of the child, or new organism conceived. One may also say of this sexual coälescence that the stem cell is a simple hermaphrodite, it unites both sexual substances in itself.” (Ev. Man, pp. 53-54.)
“The individual development,” he says, “in man and the other animals, commences with the formation of a simple ‘stem-cell,’ of this character, and this then passes by repeated segmentation (or cleavage) into a cluster of cells, known as ‘the segmentation sphere,’ or ‘segmentation cell.’” (Haeckel, Ev. Man, p. 54.)
On another page (56) he says:
“Hence the essential point in the process of sexual reproduction or impregnation is the formation of a new cell, the stem-cell, by the combination of two originally different cells, the female ovum and the male spermatozoön. The process is of the highest importance and merits our closest attention. All that happens in the later development of this first cell, and in the life of the organism that comes of it, is determined from the first by the chemical and morphological composition of the stem-cell, its nucleus and its body.” (Ev. Man, p. 56.)
“Hertwig,” he continues, “puts his theory of conception thus:
‘Conception consists in the copulation of two cell-nuclei, which comes from a male and a female cell.…’
“As the phenomenon of heredity is inseparably connected with the reproductive process we may further conclude that these two copulating nuclei convey the characteristics which are transmitted from parents to offspring.” (Ev. of Man, p. 56.)
“As, moreover, there is a complete coälescence (fusion) of the mutually attracted nuclear substances in conception, and the new nucleus formed (the stem nucleus) is the real starting point for the development of the fresh organism, the further conclusion may be drawn that the male nucleus conveys to the child the qualities of the father, and the female nucleus the features of the mother.
“We must not forget, however, that the protoplastic bodies of the copulating cells also fuse together in the act of impregnation; the cell-body of the invading spermatozoön (the trunk and tail of the ciliated cell) is dissolved in the yelk of the female ovum. This coälescence is not so important as that of the [two] nuclei, but it must not be overlooked; and though the process is not so well known to us, we see clearly at least the formation of the star-like figure, (the radial arrangement of the particles in the plasma) in it.” (Haeckel, Ev. Man, p. 56.)
In another place (p. 57) he says:
“It has been shown that the tiny sperm-cell (spermatozoön) is not subordinated to but co-ordinated with, the large ovum. The nuclei of the two cells, as the vehicle of the hereditary features of the parents, are of equal physiological importance. In some cases we have succeeded in proving that the mass of the active nuclear substance, which combines in the copulation of the two sexual nuclei is originally the same for both.
“These morphological facts are in perfect harmony with the familiar physiological truth that the child inherits from both parents; and that on the average they are equally distributed. I say ‘on the average’ because it is well known that a child may have a greater likeness to the father, or to the mother; that goes without saying, as far as the primary sexual characters (the sexual glands) are concerned. But it is also possible that the determination of the latter—the weighty determination whether the child is to be a boy or a girl—depends on a slight qualitative or quantitative difference in nuclein or the colored nuclear matter which comes from both parents in the act of conception.” (Ev. Man, p. 57.)
Haeckel continues, (p. 57):
“Quite in harmony with this new conception of the equivalence of the two gonads (ovum and spermatozoön) on the equal physiological importance of the male and female sex-cells and their equal share in the process of heredity, is the important fact established by Hertwig that in normal impregnation only one single spermatozoön copulates with one ovum; the membrane which is raised on the surface of the yelk immediately after one sperm-cell has penetrated, prevents any others from entering. All the rivals of the fortunate penetrator die without.” (Ev. Man, pp. 57-58.)