880 VEGETABLE DIET. [BOOK 11. 



behaves exactly the same upon a diet in which the proteids 

 are exclusively of vegetable origin, as upon a diet in which, 

 otherwise the same, the proteids are partly of animal origin also. 

 Nor have we much better knowledge of the relative nutritive value 

 of vegetable and animal fats. And as we have already said, we 

 possess little or no exact knowledge as to the part played by those 

 extractives in respect to the amount and nature of which animal 

 food strikingly differs from vegetable food. In attempting there- 

 fore a judgment from a purely physiological point of view as to the 

 value of an exclusively vegetarian diet compared with a diet of 

 both animal and vegetable origin, we can do little more at present 

 than inquire whether the former supplies the several food-stuffs in 

 adequate quantity, in proper proportion, and in such a form as to 

 be economically utilized by the body. 



The careful examination during three separate periods of 

 several days each of the ingesta and egesta of a man, 28 years old, 

 weighing 57 kilos, who had for three years lived on an exclusively 

 vegetable diet, viz. bread, fruit and oil, gave the following results. 



The daily diet consisted on the average of 719 grin, solid 

 matter and 1084 grm. water. It contained 



Proteids 54 grm. containing 8*4 N. 



Fats 22 



Carbohydrates 557 (about ^ sugar and J starch) 



(Cellulose) 16 



The daily faeces weighed, when fresh, 333 grm., containing 75 grm. 

 solid matter, and were therefore both bulky and watery. There were 

 present in the faeces fat 7 grm., starch 17 grm. and cellulose 9 grm., 

 shewing that 30 p.c. of the fat, 6 p.c. of the starch and 56 p.c. of the 

 cellulose had not been utilized by the body. The subject had 

 really lived on fat 15 grm., carbohydrates 540 grm. (and cellulose 

 7 grm.). The faeces contained no less than 3*46 nitrogen. If we 

 reckon the whole of this as proteid, this would give 22 grm. of 

 undigested proteid, so that there had been a waste of 41 p.c. of 

 the proteids, leaving only 32 grm. available for real use in the 

 body ; and indeed a very small portion only of this nitrogen can 

 be regarded as really discharged from the body itself. The total 

 solids of the faeces must be reckoned as partly excreta but chiefly 

 undigested food. If we regard the 75 grm. of solid faeces as 

 entirely undigested food, the whole solid food available for the 

 body must be reduced from 719 grm. to 644 grm. 



The urine of the day contained 5 '33 grm. nitrogen ; this added 

 to the 3'46 grm. nitrogen in the faeces gives 8'79 grm. nitrogen 

 in the total egesta as compared with the 8*4 grm. nitrogen of the 

 food, indicating a slight loss of nitrogenous material from the 

 body ; but if we suppose that all the nitrogen in the faeces was not 

 in the form of undigested food we may neglect this ; and indeed 



