38 THE POPULAR SCIENCE MONTHLY 



ments on monkeys showed that in health these animals have the power 

 of very quickly ridding themselves of this variety of bacteria. Experi- 

 ments now under way with a microorganism described by myself and 

 Dr. Kendall as B. infantilis and found very abundantly in some of the 

 digestive diseases of children, show the same thing to hold true. 



The fact that B. hulgaricus does not readily gain a dominant posi- 

 tion in the digestive tract in man or in the monkey has an obvious 

 bearing on the results to be expected from its therapeutic use. If it 

 be indeed true that B. hulgaricus is capable by its presence in the 

 intestinal tract of inhibiting undesirable types of bacteria and especially 

 the microorganisms concerned with intestinal putrefaction, then it must 

 be equally true that the difficulty in obtaining a dominant and perma- 

 nent foothold in the intestinal tract is a fact with which we must reckon 

 in any estimate of the results likely to be obtained through the admin- 

 istration of these organisms. The moderate representation of B. 

 hulgaricus in the large intestine after the free administration of lacto- 

 bacilline is surely something very different from what has been already 

 frequently pictured by the enthusiastic upholders of the use of this 

 form of fermented milk in the treatment of diseases of the digestive 

 tract. 



I think it has been assumed with far too little reason that the 

 dominant presence of foreign microorganisms of the lactic acid group is 

 necessarily a desirable thing. If it could be shown that lactic acid 

 bacilli, such as B. hulgaricus or certain varieties of B. acidi lactici, have 

 the faculty of replacing undesirable forms of microorganisms such as 

 the bacilli of typhoid or of paratyphoid fever or putrefactive micro- 

 organisms, such as B. proteus vulgarus or B. cerogenes capsulatus, this 

 would undoubtedly be cause for congratulation, especially if it could 

 be shown at the same time that the normal flora of the digestive tract 

 remained unchanged. I do not deny the possibility that this selective 

 kind of anti-bacterial action may some day be proved to exist. I 

 desire merely to point out that at present I know of no facts to justify 

 tis in believing that such antagonistic action as the lactic acid bacteria 

 may possess is directed solely against the disease-inciting invaders of 

 the digestive tract. If it should prove true that the antagonism exerted 

 by the lactic acid bacilli against injurious invaders is also exerted 

 against the obligate bacterial inhabitants of the alimentary canal, such 

 as B. coli communis and B. lactis cerogenes, I am by no means con- 

 vinced that this could be regarded as a point in favor of the prolonged 

 therapeutic use of lactic acid bacilli. If, as appears to be true, these 

 obligate inhabitants of the digestive tract are especially adapted to the 

 normal conditions of secretion and digestion in the human intestine and 

 tend to be suppressed in some serious conditions of the digestive tract 

 (while their reappearance and reestablishment in abundant numbers 



