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HE most remarkable fact about the internal secretions is that they are correlated with one another. Not only has this been abundantly demonstrated by experiment, but, in many cases, pathological lesions of the individual glands cause some disturbance in the functional relations of the other glands—the so-called "pluriglandular syndromes." The idea of a correlative relation is not necessarily new, was perhaps implicit even in Bordeu's statement of the theory, but it did not begin to acquire tangible and intelligible form until the complex chemistry of the metabolism of the body had beeenbeen [sic] better understood. On the physiological side, it has been noted, for instance, that excision of the pancreas produces glycosuria, even after thyroidectomy and parathyroidectomy, but not after excision of the adrenal bodies; that partial excision of the thyroid in bitches will produce a mild myxœdema, if pregnancy supervenes, the symptoms disappearing after littering; that the thymus gland is often enlarged in exophthalmic goiter but will atrophy after thyroidectomy; that castration is followed by enlargement of the thymus, and, conversely, excision of the thymus produces swelling of the ovaries. On the pathological side, the thyroid is often enlarged during puberty, menstruation, excessive venery (e. g., in prostitutes) and pregnancy; swelling of the ovary and menstrual disturbances often accompany goiter. Myxœdema often comes on at the menopause or in connection with sterility. Acromegaly, as was shown by Edwin Klebs, is often accompanied by enlargement of the thymus. Enlargement of the pituitary often accompanies pregnancy or hibernation, yet castration causes enlargement of the pituitary in the young and acromegaly is often associated with loss of sexual power. The fact that many of these experimental results and pathological findings do not harmonize makes the problem one of extreme complexity. Furthermore, it is known that lesions of different ductless glands will produce isolated identical effects, which overlap each other in a group of symptoms, making the causal relation dubious when there is a "pluriglandular syndrome." Glycosuria (lowered tolerance for carbohydrates) may be produced by goiter, by injection of thyroid extract in acromegaly or by injection of pituitary extract, by excision of the parathyroid body, by