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During the whole of this time there are no embryos in the uteri, and therefore it might be urged absorption of hormones from the embryos cannot be the cause of the persistence of corpora lutea in pregnancy. But it seems to me that a complete answer to this objection is supplied by the peculiar relations of the embryos to the pouch in Dasyurus and other Marsupials.
It seems not impossible that bones of different parts of the body give off different hormones. If the factors in the gametes were thus stimulated they would, when they developed in a new individual, product a slightly increased development of the part which was hypertrophied in the parent soma.
In Lepidoptera among insects the evidence concerning castration tends to prove that hormones from the gonads play no part at all in the development of somatic sexual characters. Exper. Zool. Oudemans had previously obtained the same result in the Gipsy Moth, Limantria dispar.
Often in serums the poison elements are retained, but not the nutritive. We use the whole goat gland, as a rule, because we do not know in what part of it the hormones hide. The attempted transplantations of kidneys have thus far failed because the kidney product is waste matter, not live cells as in the case of the interstitial glands.
The fact that a hormone from the testis affects the development of the antler, as well as our knowledge of hormones in general, suggests a special theory of the heredity of somatic modifications due to external stimuli. Physiologists are apt to look for a particular gland to produce every internal secretion.
It would be her movement a philosophy of self-containment and human empowerment to ward off loneliness, curiosity, and hormones that always stunted intelligent beings from pushing onto the next species. Guarding against these foibles, according to her, would make one less of a sociable and hedonistic monster than he or she would be otherwise.
Who would they become? As they begin to feel hormones, the adrenaline of the four-year high called love, and the frenzy of sex luring them into steady relationships and accompanying obligations, would they have moments where they too yearned to be in a hammock under their Grandma Lee's cherry trees?
We must suppose that in the beginning the sucking stimulus caused both growth and secretion, for at first there was nothing but sebaceous or sweat glands, and although a mutation might be supposed to have produced larger glands, no mutation could explain the influence of hormones on the growth and function of such glands.
On the view that both sexes and the somatic sex-characters of both sexes are present in each zygote, and that the actual sex is due to dominance, we must conclude that the male primary and secondary characters are dominant on one side, and the female on the other, and it is evident that hormones diffusing throughout the body cannot determine the development of somatic sexual characters here.
I do not claim that this theory in complete it is impossible to understand the process completely in the present state of knowledge but I maintain that it is the only theory which affords any explanation of the remarkable facts concerning the influence of the hormones from the reproductive organs on the development of secondary sexual characters, while at the same time explaining the adaptive relation of these characters or organs to the sexual habits of the various species.
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