26 HUMAN PHYSIOLOGY 



fats, starches, and sugars were classified under the 

 latter category, but the production of heat was not 

 then associated in the minds of scientific men with 

 the development of energy. In other words, food 

 which was regarded as a heat-producing element 

 was dissociated from any other of the special 

 functions we know it to discharge when consumed 

 in the body. Liebig taught the doctrine that the 

 work of the body was done on nitrogenous food. 

 He assumed, for example, in the action of a muscle 

 fed by such foods, that the muscle used up its 

 substance, and in other words developed its power 

 of movement or work out of the consumption of its 

 own material. This view held the scientific field 

 for many years, until various circumstances seemed 

 to raise doubts in the minds of physiologists 

 regarding the correctness of Liebig's views. Hence 

 arose the necessity of further experimentation. 

 This was carried out chiefly by Continental scientists 

 who practically demonstrated in a manner which 

 left nothing to be desired that Liebig was mistaken, 

 and that, as the modern doctrine of food-usage in 

 the body teaches, the nitrogenous foods are the 

 typical body-builders, whilst the non-nitrogenous 

 foods are those which represent the coal or source 

 of energy of the human machine. 



THE DEMONSTRATION. A series of experiments 

 made by two Swiss observers stands out prominently 

 as illustrating the nature of the researches which 

 gave information of paramount importance regard- 

 ing diet to the world at large. Their experiments 

 were made at the Faulhorn Mountain in Switzerland. 

 They endeavoured by practical work taking them- 

 selves as the subjects of the experiments to 

 discover the nature of the foods which were 



