Yet the fact remained that all efforts to develop the spermatozoon alone (without the agency of any egg material at all) into an individual had signally failed. Conklin[[11]] had found out in 1904 and 1905 that the egg cytoplasm in Ascidians is not only composed of different materials, but that these give rise to definite structures in the embryo later on. So a good many biologists believed, and still believe[[12,] [13,] [14]] that the egg is, before fertilization, a sort of "rough preformation of the future embryo" and that the Mendelian factors in the nuclei "only impress the individual (and variety) characters upon this rough block."
If we look at these views from one angle, the apparent conflict disappears, as Professor Conklin[[15]] points out. We can still presume that all the factors of inheritance are carried in the nucleus. But instead of commencing the life history of the individual at fertilization, we must date it back to the beginning of the development of the egg in the ovary. Whatever rude characters the egg possesses at the time of fertilization were developed under the influence of the nucleus, which in turn got them half and half from its male and female parents. These characters carried by the female across one generation are so rudimentary that they are completely covered up, in the developing embryo, by those of the new nucleus formed by the union of the sperm with the egg in fertilization.
In case fertilization does not take place, this rude beginning in the egg is lost. Since no characteristic sex is assumed until after fertilization, we may say that life begins as neuter in the individual, as it is presumed to have done in the world. It will occur to those inclined to speculation or philosophic analysis that by the word "neuter" we may mean any one or all of three things: (a) neither male nor female; (b) both male and female, as yet undifferentiated, or (c) potentially either male or female. Clearly, the above explanation assumes a certain germinal specialization of the female to reproduction, in addition to the body specialization for the intra-parental environment (in mammals).
A tremendous amount of laboratory experimentation upon animals has been done in late years to determine the nature of sex. For example, Goodale[[16]] castrated a brown leghorn cockerel twenty-three days old and dropped pieces of the ovary of a female bird of the same brood and strain into the abdominal cavity. These adhered and built up circulatory systems, as an autopsy later showed. This cockerel, whose male sex glands had been exchanged for female ones, developed the female body, and colouration so completely that expert breeders of the strain pronounced it a female. He found that simply removing the female sex glands invariably led to the development of spurs and male plumage. But simple removal of the male sex glands did not alter plumage. To make sure, he replaced the male sex glands with female, and found that the former male developed female plumage.
This obviously signifies that in birds the female is an inhibited male.[[4, p.49.]] Either sex when castrated has male feathers—the male has them either with or without testes, unless they are inhibited by the presence of (transplanted) ovaries. It will be remembered that the sociological theory of sex held by Ward, Mrs. Hartley and a host of others was founded on the supposition that evolution or development of a species is chiefly due to selection by the females of the better males, a conclusion based almost entirely on bird evidence. Ward[[17]] states that "the change or progress, as it may be called, has been wholly in the male, the female remaining unchanged"; also that "the male side of nature shot up and blossomed out in an unnatural, fantastic way...." Speaking of the highly-coloured males, especially among birds, the same writer states that "the normal colour (italics ours) is that of the young and the female, and the colour of the male is the result of his excessive variability." Goodale's results completely refute this idea, and should bury for ever the well-known sociological notion of "male afflorescence."
The general doctrine of a stable, "race-type" female and a highly variable male has been widely circulated. In tracing it back through voluminous literature, it appears to have been founded on an article published by W.I. Brooks in the Popular Science Monthly for June, 1879, fourteen years before Weissmann's enunciation of the theory of continuity of the germ-plasm. Like Wallace, Brooks continued to study and experiment till the last, and finally withdrew from his earlier position on sexual selection. However, this has not prevented others from continuing to quote his discarded views—innocently, of course.
Havelock Ellis[[18]] and G. Stanley Hall[[19]] have applied the idea of a "race-type" female with peculiar insistence to the human race. Goodale has finally killed the bird evidence upon which earlier workers so largely founded this doctrine, by showing that the "race type" toward which birds tend unless inhibited by the female ovarian secretion is the male type, not the female. There is a great difference in the way the internal secretions act in birds and in man, as will be pointed out later. It is so important that such a major point as general variability must be supported and corroborated by mammalian evidence to prove anything positively for man. As already noted, the statistical studies of Pearson and Mrs. Hollingworth et al. have yielded uniformly negative results.
In the utilization of data gathered from non-human species, certain differences in the systems of internal secretion must be taken into account. Birds differ from the human species as to internal secretory action in two vital particulars: (a) In the higher mammals, sex depends upon a "complex" of all the glands interacting, instead of upon the sex glands alone as in birds; (b) The male bird instead of the female is homogametic for sex—i.e., the sperm instead of the eggs is uniform as to the sex chromosome.
Insects are (in some cases at least) like birds as to the odd chromosome—the opposite of man. But as to secondary sex-characters they differ from both. These characters do not depend upon any condition of the sex organs, but are determined directly by the chemical factors which determine sex itself.[[20]]
In crustacea, the male is an inhibited female (the exact opposite of birds), as shown by the experiments of Giard and Geoffrey Smith on crabs. A parasite, Sacculina neglecta, sometimes drives root-like growths into the spider crab, causing slow castration. The females thus desexed do not assume the male type of body, but castrated males vary so far toward the female type that some lay eggs[[3, p.143;] [20]]. It is the discovery of such distinctions which makes it necessary to re-examine all the older biological evidence on the sex problem, and to discard most of it as insufficiently exact.