ON NERVOUS ENERGY 65 



energy. She expends on a large scale, but also produces 

 on a large scale. She has a great capacity for work, 

 which means that her system replaces the energy almost 

 as fast as it is expended. She also will have a nervous 

 system almost always highly charged. Thus one will 

 have a highly charged system because she expends little, 

 the other because she produces much. They may be 

 equally fertile or infertile. " C " is, say, a sweated worker 

 of the East End of London. She is over-worked for 

 very long hours and under-fed. The result is that she 

 is chronically tired and deficient in energy. Her nervous 

 charge will be always low. If she is married, we may 

 expect a large family. 



The variation of the degree of animal fertility in 

 response to the direct action of the environment will 

 bear an inverse proportion to the intensity of the nervous 

 charge. 



The nature of the food consumed, both quantity and 

 quality, will have a powerful effect on the amount of 

 nervous energy produced. As Snyder puts it : " There 

 is a close relationship between the nature of the food 

 consumed and mental activity, also the ability to satis- 

 factorily perform physical labour." 1 The effect of the 

 quality of the food may be seen in the difference between 

 a grass-fed and a corn-fed horse. 



The chief constituents of food are broadly divided into 

 Proteids. 

 Carbohydrates. 

 Fats. 



There are also certain salts which play a part of some 

 importance. The first of these classes is generally con- 

 sidered to be the main factor in the production of nervous 

 energy. This view receives strong confirmation from 



1 Human Foods, Snyder. 

 5 



