BIOLOGY IN HUMAN AFFAIRS 



constancy which is essential to health. Stoppage of kidney 

 function inevitably causes death. For a complete under- 

 standing of the problem of the kidneys, such questions as 

 have been outlined must be solved, and it is only when the 

 true solution is reached that we shall be able to interpret 

 kidney disease in terms of physiology, and enable physi- 

 cians better to cope with it. 



Finally, let us take a third example. In no field of 

 physiology has our knowledge grown more, have the 

 results been more spectacular, or have the practical rewards 

 to mankind been greater than in that associated with the 

 hormones formed by the endocrine or ductless glands. 

 Since the development of the doctrine of the bacterial 

 origin of disease, probably nothing has stirred up modern 

 medicine more than the doctrine of internal secretion. We 

 are told that we are what we are — bodily, mentally, 

 sexually, emotionally — largely as a result of a balance or 

 unbalance of chemical products from the glands of internal 

 secretion. Let us, then, review briefly the physiological 

 side of the modern work upon one of these interesting 

 organs. As so much has been recently written about the 

 hormones of the adrenals, thyroid, and pancreas, we will 

 take one of the less known, but no less important glands — 

 the parathyroids. 



The parathyroid glands are quite minute organs, four in 

 number, and anatomically closely associated with the 

 thyroid gland. The first clue to their function was obtained, 

 as has been the case with many of the endocrine organs, 

 by studying the effects of complete removal of these organs 

 from an animal. This operation results in the manifestation 

 of a condition known as tetany (Tetania parathyreopriva^; 

 this is in no way synonymous with tetanus. It was often 

 observed in man as the result of the removal of thyroid 

 tumors in the days before the physiological significance of 

 the parathyroids was recognized. The symptoms of removal 



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