180 SECTIONAL ADDRESSES. 



The Parathyroids. 



Another striking result from experimental work in the field of internal 

 secretion has recently been obtained in the case of the parathyroid glands. 

 Many vague and unsatisfactory statements existed in the older literature 

 as to the functions of these bodies : but now a potent extract of bovine 

 parathyroid glands accurately standardised can be obtained, and precise 

 knowledge of the part these glands play in the animal economy has become 

 possible. Extracts when injected into a variety of animals raise the 

 level of the blood-calcium ; if the injection is made into an animal that 

 has been previously parathyroid-ectomised, tetany and the usual fatal 

 outcome are prevented. Repeated or very large doses in normal animals 

 produce a condition with a definite clinical and biochemical picture — a 

 condition of ' hyper-calcsemia,' in which the blood-calcium may rise to 

 very high levels and in which a characteristic train of symptoms is found 

 with terminal renal failure. Many secondary changes occur, of course, 

 in the blood chemistry, but a closely similar if not identical syndrome is 

 produced by the simultaneous injection of large amounts of CaClg and 

 NaH2P04. 



All this work has shown beyond doubt that the parathyroid glands 

 produce a substance which is responsible for controlling the level of 

 blood-calcium, and that interference with this function by removal or 

 disease of the glands can be overcome by treatment with the potent 

 extracts now available. How this substance, manufactured by the glands, 

 produces this effect has not been completely elucidated. Much evidence 

 suggests that the rise in blood-calcium is independent of any change in 

 absorption from the gut or in the rate of excretion : Greenwald in pro- 

 longed experiments on dogs, and Hunter and Aub in men, obtained 

 indirect evidence to suggest that the rise in blood-calcium and consequent 

 increased excretion after the injection of parathyroid hormone was due 

 to mobilisation of the element from the bone reserves. 



The Ovary. 

 The gonads present the clearest evidence of the influence which a 

 tissue may exert on metabolism. I will refer only to the ovary. Virchow 

 is reported to have said that all the peculiarities of the body and mind 

 of woman, all which in the true woman we admire and revere as womanly, 

 are dependent on the ovary. Knauer showed that this organ was intimately 

 connected with oestrus and that ovarian grafting could at least partly 

 antagonise the effects of spaying. This ovarian action can be produced 

 in both sexes. If a portion of an ovary is grafted into a castrated male 

 animal the mammary glands and teats hypertrophy, the glands develop 

 to the secretory stage and the animal comes to resemble a pregnant 

 female : males so grafted become hyperfeminine in appearance. In the 

 male the development of the mammary glands is uninterrupted, the 

 Graafian follicles mature but do not rupture, and the ovary soon 

 degenerates. In the engrafted female, development is slower and, unlike 

 the male, shows a rhythm which is associated with the development of 

 the Graafian follicle, and in the regressive phase with its rupture and the 

 formation of the corpus luteum. 



