BIOLOGY IN HUMAN AFFAIRS 



In general the result of this operation is to prevent the 

 normal development of the usual male characteristics and 

 to produce an individual which is mild, strong, and heavy, 

 but incapable of reproduction. Such traits are obviously of 

 value in the Eastern harem and in the use of animals for 

 heavy w^ork and for food. And where male sopranos are 

 required for sacred music in religious worship, the choirs 

 have been maintained (until very recently, at least) by 

 surgical dedication of boys with musical talent. These 

 facts led a few curious persons to experiment with various 

 animals and with various organs, until Bayliss and Starling 

 showed how an extract of the duodenum injected into the 

 blood stream causes the pancreas to secrete, owing to the 

 effect of a hypothetical substance of very specific and 

 powerful nature to which they gave the name of hormone. 

 The idea thus established, many zoologists applied them- 

 selves to exact and well-directed experimentation, and in a 

 few years the modern science of endocrinology grew up, 

 with a new terminology, a new technique, and a new 

 knowledge and control of physiological processes which 

 had hitherto been mysterious. 



The thyroid gland, for example, produces a hormone 

 which tends to maintain normal chemical activity and 

 hence normal growth of body and mind. If this organ is 

 defective, the lack of the hormone produces sluggishness 

 and abnormal development that may result in various 

 diseases, such as myxoedema, ordinary goitre, and cretinism 

 — all more or less fully remediable by supplying thyroid 

 substance from animals. If the organ is over-developed, 

 exophthalmic goitre, great increase in basal metabolism, 

 over-activity of the heart, loss of fat, and other changes 

 occur, which can be advanced or retarded by various 

 experimental means. Much of all this was discovered by 

 research on tadpoles and other lower animals; and gradually 

 it is leading to the scientific treatment of human beings, 



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