504 VICTOR C. MYERS 



under normal conditions the feces are composed largely of intestinal 

 secretions and excretions, together with bacteria, cellular material from 

 the intestinal walls and food residues. Furthermore as Mendel (a) and his 

 coworkers have shown, the feces is the normal path for the elimination of 

 a number of foreign inorganic elements, such as strontium, barium, etc. 

 As a proof that feces are a true secretion, it has been shown by F. Voit 

 that the material secreted in an isolated loop of the intestine of a dog- 

 is of similar composition, and contains the same amount of nitrogen as 

 the feces of the normal intestine through which food is passing. Espe- 

 cially significant are the observations of Mosenthal(a), who also worked 

 with isolated intestinal loops, and estimated that the succus entericus con- 

 tained nitrogen equivalent to 35 per cent of the nitrogen ingested, and 300 

 to 400 per cent of the nitrogen of the feces. Nitrogen equivalent to at least 

 25 per cent of that of the intake must therefore have been reabsorbed. 

 Prausnitz has pointed out that the nitrogen content of the feces of the 

 same individual on a meat and on a rice diet are practically identical, 

 indicating the metabolic origin of the nitrogen. He defines normal feces 

 as those resulting from the eating of any food that is completely digested 

 and absorbed. Such foods as milk, cheese,- rice, eggs, meat, macaroni and 

 white bread are largely available for the use of the organism and conse- 

 quently yield a comparatively small amount of feces. On the other hand, 

 the cellulose containing vegetables do not possess this availability and 

 therefore yield a much more copious fecal output. Cabbage is an excel- 

 lent illustration of such a vegetable. It is logical to expect that on a diet 

 whose constituents are not entirely available, not only would the amount 

 of feces be increased by the undigested cellulose, but also the nitrogen 

 content would be increased because of the large amount of digestive juices 

 secreted, the large volume of food and the accompanying increased peri- 

 stalsis. Although the exact composition of a large part of the organic 

 material eliminated in the feces is unknown, still it is now recognized that 

 bacterial substance forms a considerable part of this material. 



The fact that about one-third of the dry matter of normal human feces 

 consists of bacteria, and at least one-half of the nitrogen of the feces is 

 bacterial in its origin, serves to emphasize the importance of bacteria in 

 the intestinal canal, though experimental evidence would indicate that 

 the presence of this large number of bacteria is a normal and even useful- 

 condition. MacNeal, Latzer and Kerr, who have devoted considerable 

 attention to the bacterial content of the feces, find that in normal subjects 

 the bacterial dry substance varies between 1.8 and 9.2 grams with an 

 average of 5.3 grams per day, while the bacterial nitrogen ranges between 

 0.2 and 1.0 gram with an average of 0.6 gram, this latter figure constitut- 

 ing 46.3 per cent of the fecal nitrogen. Of the fecal bacteria they find 

 that 80. Y per cent are Gram negative (45,0 per cent B. coli type), 17.0 



