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The year was 1855 when Thomas Addison was conducting autopsies on humans. He noted that people who had atrophied adrenal glands, meaning shrunken adrenal glands, had shown signs of poor appetite, low blood pressure, weakness, anemia and a bronze coloring of the skin. From these patterns he had observed, his conclusion was that the adrenal gland must have been releasing something that prevents these symptoms in the first place. He was indeed correct as our society today now knows that this was the case with the adrenal glands in humans.
Dolanski, in the year 1894, was the one who laid out the foundation for hormones. Mr. Dolanski tried to insert acid into the rectum of a dog, into it's intestine, in order to stimulate digestive juice acids. This didn't work. What was the reason? The reason was that it was the hormones that needed to do the trick in order for it to work properly.