FERMENTED MILKS. 3 



come established there in large numbers. In the normally nourished 

 infant the bacterial varieties are limited in number and for the most 

 part consist of acid-forming types which by the active fermentation 

 of the milk sugar furnished in large quantities in the food produce 

 conditions under which bacteria of the putrefactive type are unable 

 to multiply to any extent. The predominance of an acid fermenta- 

 tion in the large intestine produces an acid stool with a characteristic 

 but comparatively unobjectionable odor. As the child gets older the 

 variety of food is greater and the relative proportion of carbohy- 

 drates to protein is much reduced. In place of the acid fermentation 

 there is a decomposition of the protein by other bacteria, intestinal 

 gas is produced, and the stools become alkaline and frequently have a 

 very objectionable odor. In the bacterial decomposition of the predi- 

 gested protein it is supposed that products of a more or less toxic 

 nature are produced. When the quantity of these products is rela- 

 tively small they are disposed of through the normal channels and 

 have no appreciable effect. If the excretory system fails to do its 

 normal work, or if the protein decomposition is unusually active, 

 toxic substances accumulate and the symptoms of autointoxication 

 are produced. The production of toxic substances in abnormal 

 amounts may be caused by a combination of circumstances promot- 

 ing an unusual activity of putrefactive bacteria normally present, or 

 it may be because the bacterial flora of the intestines changes and new 

 bacteria are introduced. 



The method of treating this condition by the use of sour milk is 

 based on three conditions which may be stated as follows: (1) It 

 iissumes as correct the theorj^ of the production of toxic substances 

 in the intestine by the action of bacteria in quantities sufficient to 

 cause the symptoms of autointoxication; (2.) the putrefaction or 

 fermentation through which these toxic substances are produced can 

 be suppressed by other bacteria; and (3) the bacteria which it is 

 proposed to use in suppressing the putrefactive bacteria may be 

 introduced into the intestines and will be able to establish conditions 

 there under which they will multiply and persist, while the objec- 

 tion able types are driven out. 



The standing of the theory of autointoxication mentioned under 

 the first condition can not be discussed in detail in a paper of this 

 nature. It may be said, however, that the question of autointoxica- 

 tion, in its broader sense, is not nearly so simple as it is stated here. 

 It is at best only a theory, and much investigation of details will be 

 necessary before its position can be determined. 



The second condition is easily demonstrated, not only by scientific 

 observation, but also by many instances in our daily life. Vinegar, 

 which is used in pickle making, owes its preservative action to the 



