14 INFECTIONS OF THE DIGESTIVE TRACT 



with Bienstock's B. putrijicus quite richly without any 

 evidence of putrefaction, although the organisms are 

 kept under anaerobic conditions. Although this observa- 

 tion points to the absence of putrefactive processes, 

 it must be remembered that the growth of anaerobes is 

 relatively difficult where the quantity of moisture is 

 limited, as in the case of the foregoing experiments, and 

 also that the quantity of nutrient material available 

 for the growth of putrefactive anaerobes is small in the 

 movements of normal milk-fed children. A similar 

 result is obtainable after inoculating concentrated 

 fseces-agar with various bacteria, such as pyocyaneus, 

 prodigiosus, the bacillus of Friedlander, the vibrio of 

 Metchnikoff, and various strains of the typhoid bacillus. 

 That is to say, such f seces-agar richly inoculated with the 

 foregoing organisms fails to show any growth, whether 

 the acid reaction of the medium be retained or whether 

 neutralization has taken place. On the other hand, it 

 has been noted that B. coli, B. fluorescens, Staphylococcus 

 intestinaliSj streptococcus, proteus, and the paracolon 

 organisms, as well as putrificus are apt to grow some- 

 what better. From this observation one may perhaps 

 reach the conclusion that the bacteria of the intestinal 

 tract possess an elective antagonistic action against 

 foreign types of microorganisms. 



An effort has been made to obtain an adequate ex- 

 planation for this behavior, and especially to determine 

 whether the inhibition for bacteria here noted depends 

 on the production of definite bactericidal substances. 

 The methods employed by Moro and Murath were 



