INFECTIONS OF THE DIGESTIVE TRACT 335 



which has been studied by Professor Metchnikoff. 1 It is 

 capable of inducing a high grade of acidity in milk, but 

 does not grow readily on other media. This lactic- 

 acid producer is said by Professor Metchnikoff to be 

 entirely harmless and has been used by him and his as- 

 sociates as a means of lowering the putrefactive processes 

 in the digestive tract. One feature of superiority claimed 

 for Bacillac is that it does not contain any yeasts. This 

 is a point of some importance, since it is probable that 

 some of the fermented milks do contain yeasts capable 

 of exerting a detrimental action on the human organism. 

 Whether the Bacillac preparation will show itself to be 

 superior in a therapeutic way to other fermented milks 

 from which undesirable yeasts have been excluded 

 must be regarded as an open question and one that can 

 be decided only by extensive and very careful ex- 

 perimentation. There is certainly much to recom- 

 mend the view that putrefactive intestinal processes 

 are favorably influenced in their clinical course by 

 fermented milk containing an abundance of lactic 

 acid and lactic-acid organisms. The subject is one, 

 however, which is very far from resting on a scientific 

 basis, and a large amount of most careful research is 

 necessary to establish the exact position of this prin- 



1 Dr. Collins found the organism to be Gram-positive, similar 

 to B. aerogenes capsulatus in morphology, but larger and incapable 

 of making indol or hydrogen sulphide. The presence and growth 

 of this organism in milk flasks inoculated with human faeces con- 

 taining an excessive number of gas-bacilli appeared to exert a 

 restraining effect on putrefaction. The maintenance of an acid 

 reaction is essential to this restraint. 



