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These traits appear only when the hormones occur which are present in one sex and that only when the gonads of that sex are mature. In some cases they appear only at the period of the year when reproduction takes place, disappearing again after the breeding season. After castration, the hormones being absent, all these points of contrast between the sexes fail to appear.
Even if he had accomplished nothing else he had struck a note which had caused the Athertons to forget their former superciliousness. "If there is an oversupply of thyroid hormones," continued Craig, "that excess will produce many changes, for instance a condition very much like exophthalmic goiter.
The hormones reply to every call of life and respond in every reaction. The normal constructive process of their cells remanufactures what has been lost, and the original capacity to respond is restored. If, though, the rate of destruction and loss outruns the rate of repair and construction, they will be permanently damaged.
Here again the hormone theory, although we cannot pretend to understand the matter completely, helps us to form a conception of the process of heredity and evolution. The disuse of legs in the larva affects the determinants, so that they remain inactive in the presence of the hormones produced in the body generally in this stage.
The differences in the original hormones of the modified parts are therefore acting simultaneously with the hormones, that is, the chemical substances derived from all other parts of the body in its fully developed condition.
It is very probable that in the early stages of development the metabolism of the body would be considerably different from that of the adult stage, and the same combination of hormones would not be present.
Theory supposes that somatic modifications by means of hormones affect the determinants in the gametes. But it is obvious that the black and white of Leghorn fowls and of guinea-pigs are gametogenic characters, and are strongly established in the gametes of their respective varieties.
They are called hither and thither partly by messenger-substances thrown into the blood, known as hormones, partly by the "smell of the battle afar off," the toxins of inflammation and infection as they pour through the blood. The red ones lose their nuclei, their individuality, in order to become sponges, capable of saturating themselves with oxygen and carrying it to the gasping tissues.
Melatonin taken at bedtime really does help me get to sleep and may have remarkable life-extending properties. Other amino acids help my body manufacture growth hormones and I use them from the time I begin training seriously in spring through the end of the summer triathlon competition season. The Future Of Life Extension
The adrenals tire, becoming incapable of dumping massive amounts of stress-handling hormones or of repeating that effort time after time without considerable rest in between. The consequences of these inter-dependent deterioration's is a cascade of deterioration that contributes to even more rapid deterioration's. The name for this cascading process is aging. Its inevitable result death.
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