106 PHYSIOLOGY CHAP. 



muscular and psychical faculties necessary for victory in the 

 struggle for existence." The alimentary regimen tried for nine 

 months by Chittenden and his fellow-workers professional men, 

 students, and soldiers was sufficient to give a nitrogenous balance 

 not of the first but of the second kind, as is obvious from what 

 we have already said on the subject. Let our critic try to follow 

 the example of these good people ; he will lose part of his useless 

 stored-up reserves and thick compact adipose layer which have 

 increased the weight of his body and marred the Apollo-like lines 

 of youth, but as compensation he will gain a greater degree of 

 vigour in all his functions, including the sexual function to which 

 he rightly attaches great social importance. 



V. What we have said so far about the composition of human 

 food applies to the ordinary mixed diet, in which the proteins, 

 fats, and carbohydrates are derived from various articles of food 

 whether they be of vegetable or animal origin. We must now 

 deal briefly with the question whether a diet which is mainly 

 vegetable or one which is mainly animal is more natural and 

 hence more physiological and useful to man. 



From the fact that the digestive organs of man resemble more 

 closely those of carnivorous than herbivorous animals, some 

 physiologists have argued that man was originally carnivorous and 

 became omnivorous and even vegetarian owing to the Varying 

 conditions of the environment in which he was forced to live. 

 This seems to me a wholly erroneous induction. 



If we wish to form an idea of primitive man, whatever theory 

 of descent we adopt, we should compare him not with the 

 domestic animals, but the anthropoid apes living in a state of 

 nature. Now it is well known that apes live upon an almost 

 exclusively vegetarian diet; roots, seeds, and more especially 

 fruits, form the basis of their nutrition, although they also indulge 

 in eggs, small birds from the nest, and the larvae of insects. 

 They are, in short, frugivorous and fruitivorous, with a tendency 

 to become omnivorous. In all probability, therefore, man, who 

 represents a higher stage of evolutiou, was originally omnivorous, 

 but can readily become vegetarian or carnivorous, according to the 

 latitude in which he is compelled to live and the flora and fauna 

 found there. 



The physiological proof that man more readily adapts himself 

 to a vegetable than an animal diet is afforded by the fact that 

 whereas it would be impossible for the civilised human races to 

 live for any length of time on an exclusively animal diet on 

 account of the inadequate digestive power of the alimentary 

 canal, they can easily live, work, and prosper on a purely vegetable 

 diet. The only exceptions to this rule are certain primitive 

 tribes, such as the Bushmen, the Eskimos of Greenland, the 

 Ostiaks, the peoples of the shores of the Eed Sea, the shepherds 



