652 LECTURE XXVIII. 



alone and to maintain it at the highest stage of bodily and mental vigor. 1 

 A diet consisting entirely of vegetables is inadvisable for the following 

 reasons: In the first place, vegetables are not utilized very advantageously, 

 as the above tables show; this is particularly true of the protein which they 

 contain. It must be stated, however, in this connection, that the values 

 in the tables were determined solely by the amount of nitrogen in the food. 

 This is not quite right, for meat contains nitrogenous extractive substances 

 which are not of an albuminous nature. For this reason the values given 

 for the protein in the meat were a little too high. This, however, does not 

 materially influence the comparison. A vegetable diet has the further 

 disadvantage that it lacks savor. To be sure, this may be remedied by 

 artificial additions, and by exercising especial care in the preparation of 

 the food. A vegetable diet is especially objectionable on account of the 

 greater volume of the food. 



All our present knowledge, both from the standpoint of experiments on 

 metabolism and practical experience, justify us in assuming that a mixed 

 diet is to be preferred as food for a people. There is no reason why we 

 should attempt to eliminate animal food from our rations. 



It has never been positively proved that a flesh diet, even when it pre- 

 ponderates, is harmful. All statements with regard to the injurious effects 

 of a meat diet are based upon indirect conclusions, which are capable of 

 two interpretations. We must admit that the human organism is capable 

 of deriving sufficient nourishment from a vegetable diet, if it is provided in 

 sufficient quantity. It does not seem true, from the above experiments, 

 that the organism accustoms itself to vegetable food in the sense that the 

 vegetable material is consumed to better advantage after a time. It would 

 not be at all advisable, on the other hand, to restrict the diet for any length 

 of time to meat, and chiefly because of the fact that there is then a lack 

 of material which tends to promote the peristalsis of the intestines. In 

 the case of the carnivora, the same effect as that produced by cellulose is 

 obtained from the fragments of bone and other difficultly-digestible material 

 which the animal swallows with its food. 



The whole question concerning the relative advantages of vegetable, 

 meat, or mixed diets rests largely upon one important point, namely, which 

 kinds of material are utilized in the body to the best advantage. We have 

 again and again stated that the food does not, under normal conditions, 

 become part of our bodies in the form that it is eaten, but it is the con- 

 stituents which result from a complete disintegration of the food that are 

 suitable for the body. All nourishment is eventually assimilated in our 

 tissues. If we hold to the standpoint that the tissue cells of course in 

 a restricted sense are quite independent of the nature of the food which 



1 Cf. Caspar!: loc. cit. p. 122. 



