THE GASTRO-INTESTINAL FLORA OF NORMAL INFANTS 595 



antitoxins can be prepared; sera likewise have been unsatisfactory. 

 There is little, therefore, that can be accomplished serologically 

 with present methods in the treatment of intestinal disturbances of 

 bacterial causation. Attempts to permanently eliminate or destroy 

 undesirable bacteria with cathartics and intestinal antiseptics have 

 not been productive of results in the past 1 and prolonged starvation 2 

 per se does not lead to intestinal sterility or to a significant reduction 

 in the offending bacteria. 



FIG 97. Bacillus bulgaricus. (Photograph by Dr. J. H. Stebbins, Jr., from the 

 Fairchild culture of the Bacillus bulgaricus. 



There are two ways, however, in which direct influence may be 

 applied to bacteria in the intestinal tract: By a substitution of harm- 

 less types of organisms for abnormal types, and by varying the diet 

 of the host in such a manner that the intestinal contents at the desired 

 level shall contain nutritive substances that may be reasonably 

 expected to shift the metabolism of the offending organism, and 

 therefore radically change the character of the products of its 

 metabolism. 



A substitution of bacteria may be accomplished, theoretically at 

 least,, either by feeding cultures of organisms whose products of growth 



1 Kendall, Jour. Med. Research, 1911, xxv, 149, for brief resume. 



2 Even after thirty-one days' starvation, a large number of viable bacteiia were found 

 in the lower part of the intestinal tract of the one case studied with this possibility in view. 



