Science: Sex Life of Achlya

The existence of sex hormones is one of the most widely-known discoveries of modern biology. Androsterone and testosterone make a man manly, progesterone and estrone make a woman womanly. But in man and other highly evolved animals, the ordinary processes of life depend on other hormones which are non-sexual—such as insulin, the sparkplug hormone from the pancreas. Growth, according to the Carnegie Institution's Oscar Riddle, is due to a combined action of two pituitary hormones, prolactin and thyrotropin.

Growth hormones have been discovered in plants. The major ones are "Auxin A," "Auxin B" and "Heteroauxin." Academic research on plant-growth hormones, mainly done...

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