BIOLOGY IN HUMAN AFFAIRS 



germs gain their effects by their toxins. Here also there is 

 much to be learned concerning the nature of the germs 

 responsible for such diseases and the nature of the remedies 

 to be used against them. 



Whenever new discoveries are made in any field of 

 science, they are promptly applied to the possibilities for 

 the alleviation and the cure of disease. Recent years have 

 seen two special trends of utmost importance, one having 

 to do with the determination of the deficiency diseases 

 and their control by vitamins; the other having to do with 

 the effects of great physical forces. 



It is now known that such diseases as xerophthalmia, 

 pellagra, polyneuritis or beri beri, scurvy, and rickets 

 may be due to the deficiency of certain vitamins in the diet. 

 They occur when these vitamins are absent, and the con- 

 dition is cured when the necessary vitamin is supplied. 

 Little is known as to the effects of relative deficiency of 

 vitamins, but unquestionably this is associated with the 

 possibility of lessened resistance to infection and minor 

 complaints not yet perfectly recognized. It seems likely, 

 furthermore, that there must be many more vitamins than 

 those already discovered, just as there are many more 

 unknown specific organ substances having to do with the 

 growth and nature of the human body. 



From the thyroid gland, the pancreas, the parathyroid 

 gland, the adrenals, the testis, and the liver, extracts have 

 been developed which control diseases formerly considered 

 fatal. Pernicious anemia is overcome by liver extract; 

 myxedema by thyroid extract; Addison's disease by an 

 extract from the adrenal. Unquestionably, each one of the 

 glands secretes several, if not many, hormones; and the 

 isolation of all of them not only as extracts, but also as 

 pure chemicals, represents the necessary research of the 

 near future. 



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