INFECTIONS OF THE DIGESTIVE TRACT 87 



of study by means of modern methods. That a knowl- 

 edge of the influence of different foods upon the flora 

 in health and disease would not only be of great bio- 

 logical interest but would also give many indications 

 of a practical sort for the use of different types of 

 foods in pathological conditions, requires no argument. 

 Some observations have been recorded upon the influ- 

 ence of food which have led to the conclusion that there 

 is little difference between a, diet consisting of vegetable 

 food on the one hand and a mixed diet with abundance 

 of meat on the other. The methods employed for de- 

 termining the presence of differences in the character 

 of the flora were, however, so crude that the work in 

 question cannot be regarded as in any manner conclusive. 

 I have observed that the number of Gram-positive 

 organisms in the faecal fields was much increased when 

 an adult subject who had previously been on a mixed 

 diet began to live on a dietary consisting almost exclu- 

 sively of meat. The microscopical appearances indicated 

 that an increase in the number of putrefactive anaerobes 

 was largely responsible for the change from a mixed 

 faecal field to one which was dominantly Gram-positive. 

 In this connection I think the observation noteworthy 

 that the intestinal contents of animals living on a diet 

 of raw meat tend to give mixed or dominantly Gram- 

 positive fields, whereas similar material from herbivo- 

 rous animals tends to give fields in which Gram-negative 

 organisms are predominant. As mentioned in connection 

 with the discussion of the faecal flora in herbivorous 

 animals as compared with carnivorous animals, there is 



