66 TRANSFORMATION OF THE INTESTINAL FLORA 



cultural tests furnish the more reliable information as to the actual 

 bacterial activities within the alimentary canal, owing partly to the 

 uncertainty of identification of the more important organisms by 

 morphology alone, and partly to the fact that an examination of the 

 Gram-stained film can offer no clue regarding the viability of the bac- 

 teria. The relative number of viable bacteria in human feces, as com- 

 pared with the total bacterial content, is extremely small, as has been 

 shown by various investigators. McNeal, Latzer and Kerr (1909) 

 have estimated it at about one to three thousand. The absence in some 

 instances of complete correlation between the results of the direct and 

 indirect methods of determination of intestinal flora is in all probability 

 due to an unusually large proportion of dead bacteria. 



BASAL DAILY DIET 



In order to determine the influence of the ordinary daily diet on the 

 types of bacteria commonly developing within the alimentary canal the 

 stools of subjects C and I were examined for ten and fifteen days 

 respectively. Throughout the observation period these individuals 

 were found to harbor the ordinary complex flora. (See Tables 25 and 

 26.) B, acidophilus was present in extremely small numbers. Subjects 

 A and D, who had been consuming as part of their regular daily diet one 

 half to one quart of milk daily for weeks and perhaps months prior to 

 the experiments, were instructed to continue the use of a quart of milk 

 daily for ten days. These subjects carried a relatively high proportion 

 of B. acidophilus, and the amount of gas production in the Veillon tubes 

 was considerably less than in the tubes of C and I. Upon the removal 

 of the milk from the daily regimen the percentage of B. acidophilus 

 dropped gradually until there was a complete reversion of the fecal 

 flora to the ordinary mixed type as seen in subjects C and I. (See 

 Tables 27 and 28, and Chart 30.) 



The examinations of the stools of subjects A and D supported the 

 claims of Hull and Rettger and others that B. acidophilus is a normal 

 inhabitant of the intestinal tract of man. We have had no difficulty 

 in later experiments to demonstrate again and again this important and 

 fundamental fact. Under ordinary conditions of diet, however, the 

 organism is present in very small numbers, and requires a dietary 

 stimulus or bacterial reinforcement to incite it to increased activity. 



The ordinary daily diets of the various subjects employed in this 

 investigation have been well suited for studying the simplifying influence 

 of the various test agents, inasmuch as they encourage the development 

 of the so-called putrefactive and gas-producing organisms, and only in 

 a very slight degree or not at all B. acidophilus. With such diets as the 

 starting points, the administration of the various test materials which 

 have a transforming influence in the direction of simplification of flora 



