734 PHYSIOLOGY 



that the ' stimulant ' effect of proteins on metabolism might have 

 a real value to the organism. 



The limitation of protein diet to a minimum is only justifiable 

 in adult healthy men. Where from any cause there has been a 

 loss or destruction of nitrogenous tissue, as after infective diseases, 

 the body possesses the power of storing up nitrogen in the form of 

 flesh or muscular tissue, and it is important under such circumstances 

 to give in the food an excess of protein which can be used for this 

 purpose. Moreover, when a rapid growth of muscle is going on, 

 as during training, an excess of protein in the food is also desirable, 

 though nothing is gained in pushing this administration of protein 

 to an inordinate extent. 



The fact that in many cases greater economy and efficiency of 

 nutrition are attained by diminishing the protein of the diet affords 

 no argument for accepting or rejecting any given class of foods. Thus 

 the normal requirements of the individual can be obtained by the 

 administration of a diet containing meat, eggs, vegetables, and cereals, 

 or by a diet derived entirely from the vegetable kingdom. A purely 

 vegetable diet is rendered possible in civilised countries by the ease 

 with which the products from warmer climates can be obtained. 

 A diet composed only of the products of temperate climates would 

 tend to be deficient in fats and oils. In such climates it is therefore 

 necessary to import the oily fruits grown in warmer lands, or to 

 supplement the diet with such animal food as milk or butter or eggs. 

 In drawing up a purely vegetarian diet it is important to remember 

 that Jts constituents, especially its protein, are digested with greater 

 difficulty than the corresponding ingredients in animal food. A 

 larger quantity therefore has to be given in a vegetable diet in order 

 to allow for the greater loss by the faeces. Any general reform of 

 diet which may be indicated by recent physiological experiments 

 would seem to lie rather in the direction of limitation of the quantity 

 of different articles of food, perhaps especially of those rich in protein, 

 than in a limitation to foods obtained from the animal or vegetable 

 kingdom. In certain individuals the increased bulk of indigestible 

 residue which is afforded on a vegetarian diet presents a distinct 

 advantage, since it serves to promote peristalsis and the normal 

 evacuation of the large bowel. There is no scientific evidence that 

 for the ordinary person any advantage is to be gained by adherence 

 to a strictly vegetarian diet. 



THE DIET OF THE GROWING ANIMAL 



Since the young animal is smaller than the adult, it presents a 

 greater surface in proportion to its bulk, and therefore will need 

 more energy per kilo body weight than is the case with the adult. 



