DIET AND BACTERIAL FLORA 235 
secreted. Toida (1914) found that bile of man and dogs was normally 
sterile and that it was not a satisfactory medium for all bacteria. It 
was only slightly suited to Staphylococcus pyogenes aureus and Ps. 
pyocyaneus. Streptococcus pyogenes and Dip. pneumonie were better 
adapted to it. The bactericidal action was found to vary with 
the origin. Just below the pomt of entrance into the intestine, the 
bacterial flora is much simpler. JB. colz is often the predominating form. 
The regulation of carbohydrate fermentation by bile has been 
studied by Roger (1912, 1913, 1915). The hydrolysis of starch was 
increased up to 30-40 per cent but when smaller amounts (10 per cent) 
were used there was a retardation. Heating the bile did not destroy 
its activity. Moderate amounts of bile (5-20 parts per 100) retarded 
the action of intestinal bacteria on glycogen. Larger amounts were 
erratic, causing sometimes a retardation and sometimes an increase in 
the action. The same was found to be true with regard to glucose. 
Pure cultures of Bacillus colon were inhibited in their action on glucose, 
moderate amounts exerting a more consistent retarding effect than 
larger amounts. 
Bile also exerts a retarding effect on putrefaction. Roger (1913) 
found that the intensity of the biuret reaction of protein media inocu- 
lated with intestinal bacteria in the presence of different amounts of bile, 
showed that the attack on proteins was retarded. This retardation was 
evident up to concentration of 20 per cent after which the retardation 
decreases. Roger (1915) regards the bile as a factor tending to diminish 
the production of bacterial enzymes and neutralizing toxins. Boudielle 
(1913) reported that bile as well as bile salts had an inhibiting action on 
the fermenting power of B. coli on glucose. Moderate amounts had 
more pronounced effects than greater amounts. Lagane (1914) added 
bile to bouillon cultures and noticed no retardation in growth of intes- 
tinal bacteria. He claimed that it favored the development of B. colz 
at the expense of other species. 
Whether the bile is a germicidé seems hardly to have been settled. 
However, most of the data which have been accumulated seems to show 
that bile exerts a selective action. Toida found that under normal 
conditions the bile to be sterile. In this connection, it is interesting to 
remember that gall stones may be started by bacteria and that very 
often typhoid carriers liberate the bacilli in the bile. In these instances 
the bile seems to exert no bactericidal action, but perhaps a selective 
action. 
Effect of Diet on the Intestinal Flora. It has long been considered 
that diet was one of the most important factors determining the intes- 
