218 MAN AN ADAPTIVE MECHANISM 



sympathy. In the modern environment, where there 

 is a minimum of action and a maximum of restraint 

 of action, man is in auto-captivity to phylogenetic tend- 

 encies. The consequent excessive and continuous 

 stimulation of the heart and blood vessels, of the 

 brain, thyroid, adrenals and liver, together with the 

 coincident excessive and continuous inhibition of the 

 digestive processes and the accumulation of unused 

 secretions and waste products, leads frequently to 

 certain organic degenerations. 



An interesting phenomenon, from a biologic view- 

 point, is the fact that it is in man more often than in 

 woman, that increased energy transformation leads to 

 cardiovascular disease, diabetes and nephritis. Man, 

 more than woman, is subject to cardiovascular and 

 cardiorenal disease ; to thrombo-angiitis obliterans and 

 to diabetes. Woman, on the other hand, is the more 

 frequent sufferer from diseases of the thyroid gland. 

 In this proneness of woman to diseases of the thyroid 

 and of man to diseases caused by hypertension, we 

 have a curious instance of pathologic modification 

 along lines of adaptation. 



The adrenals preeminently control the mechanism 

 for increasing motor efficiency during short periods of 

 increased transformation of energy. The adrenals are 

 the organs most heavily involved in muscular work. 

 On the other hand, the thyroid controls the mechanism 

 which regulates energy transformation during longer 

 periods of increased activation. It is known that the 

 thyroid enlarges during sustained periods of increased 

 activity, especially during infection, adolescence and 

 pregnancy. Throughout the ages of evolution, the 



