1913] Chemistry of Diet 185 



as produced hy fermentation are at worst but irritants and are 

 for the most part non-nitrogenous. It would appear, therefore, 

 that the production of toxic substances of bacterial origin must 

 be the result of proteolytic putrefactive activity rather than of 

 fermentative activity. 



The importance of the saving action of carbo-hydrate 

 for protein in the light of toxin production must be 

 apparent. In this connection again, Osborne and Men- 

 del have attributed great importance to the bacterial flora in 

 their success in maintaining animals on what we might call 

 insufficient food. In the first place, they have reported what 

 has many times been observed, i. e., that their caged animals, 

 living on an artificial and under-nourishing diet, will eat of their 

 own feces. Furthermore, they report the interesting observa- 

 tion that their animals fed on a stunting diet, will eat the feces 

 of other rats rather than their own, when the opportunity is 

 oft'ered. In a number of such cases, they have observed an im- 

 mediate improvement in the rate of growth, while the diet 

 remained constant. This gain in utilization of the food, they 

 have attributed in such cases to a new acquisition of bacteria. 

 By way of illustration : Their maintenance diets for the albino 

 rats, were purine-free and they advance the hypothesis that prob- 

 ably the bacterial flora played an important part in such synthe- 

 sis as the purines. Quoting Herter : ''The number of bacteria 

 in the daily excreta of man has been estimated as aj)proximate- 

 ly 126 billion." Such an amount of bacterial activity cannot 

 be overlooked in the chemical production or synthesis of definite 

 compounds. Osborne and Mendel suggest that probably the 

 bacteria are able to synthesize some of these necessary com- 

 pounds which, without them, would be unavailable for epithelial 

 absorbtion. In other words, when the animal under dietary 

 study is observed to exist on a purine and lipoid-free diet, 

 possibly those substances become available for absorbtion in 

 the intestinal tract from the disintegration of bacterial bodies. 

 McCollum has recently demonstrated the long maintenance 

 of hens on a chemically fat-free and lipoid-free diet. Under 

 these conditions, pounds of eggs, during successive weeks, were 



