vi INTESTINE AS AN OBGAN OF EXCEETION 357 



As these figures show, the percentages of nitrogen, of ethereal 

 extract, and of ash constituents vary within narrow limits, 

 independent of the nature of the diet. This appears both from 

 the five individuals accustomed to an ordinary mixed diet, and 

 from the vegetarian who had been nourished for many years on 

 vegetable foods only (plus milk, eggs, and butter). 



Seeing that in all these individuals the nitrogen content of 

 the faeces oscillates between 8 and 9 per cent, both on an 

 exclusively vegetable diet (rice and fine wheat bread) which only 

 contain about 1/5 per cent nitrogen, and when a comparatively 

 large amount of meat was added in which the percentage of 

 nitrogen is much higher, we have a new argument in support of 

 the theory of Voit and his school, to the effect that normal 

 faeces consist almost exclusively of katabolic products from the 

 intestine. 



Prausnitz gives the name of normal faeces exclusively to 

 those obtained on a diet of substances which can be almost com- 

 pletely digested and assimilated, and in which the percentage of 

 nitrogen fluctuates between 8 and 9 per cent. When less readily 

 absorbable vegetable foods are ingested, the percentage of nitrogen 

 in the faeces falls considerably (to 4*3 per cent), in proportion 

 with the amount of non- digested alimentary residues present. 

 In a few rare cases the percentage of nitrogen may increase, as 

 occurs on feeding substances which are not very absorbable, and 

 which contain a large amount of nitrogen. 



Accordingly, the composition of the faeces is never in ratio 

 with that of the diet. Even on a diet which is badly digested and 

 ill absorbed, the faeces formed always (in consequence of the 

 excretion of large amounts of intestinal juice, which mixes with 

 the alimentary residues) contain a relatively large amount of 

 nitrogen in comparison with that of the food ingested. In the 

 apparent exceptions to this rule, the relatively low nitrogen 

 content of the faeces depends on the relatively high content of 



