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Updated: July 17, 2025
The zygote therefore, whether the sex of it is determined as male or female, has the same factor for the development of milk glands. On the chromosome theory as formulated by Morgan this factor must be in the somatic chromosomes and not in the sex-chromosomes, and must be present in every zygote.
How far Doncaster is right in holding that the soma is different in the two sexes is a question already mentioned, but it is obvious that in each individual the somatic sexual characters proper to its species are present potentially in its constitution by heredity in other words, as factors or determinants in the chromosomes of the zygote from which it was developed; but the normal development of such characters in the individual soma is either entirely dependent on the stimulus of the hormone of the gonad or is profoundly influenced by the presence or absence of that stimulus.
As you have seen so many North American Indians, you will be able to give interesting explanations of their somatic relations to the South American Indians. Why could you not send me, as secretary of the mathematical and physical section, a short report of your principal results?
Perhaps the most remarkable of all somatic sexual characters are those which are almost universal in the whole class of Mammalia, the mammary glands in the female, the scrotum in the male.
In order to bring the question to a decision, it was only necessary to have one other circumstance, viz., a regular concurrence of the inversion with the psychic and somatic signs of hermaphroditism. But this second expectation was not realized. The relations between the assumed psychical and the demonstrable anatomical androgyny should never be conceived as being so close.
Perhaps something can be obtained if we limit ourselves to a study of cases with pronounced somatic renal symptoms and signs, cases with the renal facies and the like. As to the question of phthisis and mental disease, Ziehen remarks that the tuberculous are often observed to be optimistic but that other cases show a hypochondriacal depression with egocentric narrowing of interests.
One of these is to graft ovaries or testes from one animal into another which possesses a certain somatic character, and then to see if the offspring produced from these gonads shows any trace of the character of the foreign soma in which it was nourished. Exper. He grafted the ovaries of two Black Leghorn pullets into two White pullets of the same breed, and vice versa.
Professor Weismann does indeed go on to say that this influence must be extremely slight, but we do not care how slight the changes produced may be, provided they exist and can be transmitted. The same applies here, if stirring events that occur to the somatic cells can produce any effect at all on offspring.
Among these are counted all sorts of compulsive neuroses, compulsive thoughts, compulsive behavior and cases of hysteria, where phobias and obsessions play a chief role, also somatic phenomena of hysteria which do not need to be acted upon quickly, such as, for example, anorexia. In acute cases of hysteria it is better to wait for a calmer period before applying psychoanalysis.
Spermatogenesis is not the only source of the testicular hormone: changes in the secretory activity of the interstitial cells or spermatocytes are sufficient to account for periodic development of somatic sex-characters, and the same reasoning applies to the antlers of stags. The milk glands in Mammals constitute one of the most remarkable of secondary sexual characters.
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