22 
neutral red glucose broth. From these tubes, isolated colo- 
nies were obtained by planting out on bile salt glucose agar. 
144 colonies from these 12 samples were tested as to their 
power of fermenting glucose and lactose. Out of these 144 
colonies, 138 or 95°5°% fermented lactose and glucose ; 6 or 
4°5°% fermented glucose but not lactose. 
Series IV.—A precisely similar experiment was carried 
out with 12 samples of cowdung. Out of 144 colonies treated 
in this way, 135 or 93°8% fermented both glucose and lactose ; 
9g or 6:2% fermented glucose but not lactose. 
In no case in any of these series (derived from 46 different 
samples of feeces and no less than 710 colonies) did a single 
organism that fermented lactose not ferment glucose, and no 
specimen of bacillus that fermented neither lactose nor glucose 
was obtained. 7 
These results obtained from feces are sufficient to show 
that by far the most important organism in feces is a class 
of organisms that ferment both lactose and glucose; that in 
both human feces and cowdung the class lactose— glucose + 
is distinctly rare and did not form more than about 5% of 
the intestinal flora at this time of year. It may be stated 
that these experiments were carried,out in 1909. As we have 
shown previously in all work on feeces it is extremely danger- 
ous to say that any particular variety of organism is always 
present in faeces in any constant percentage; it was very 
desirable to confirm the previous results by further inves- 
tigations. In the months of February and March -Io1r, 
a further series of colonies were collected. Some of these 
were put through glucose broth, and plated out on lactose 
solid medium, and some were plated out direct on to a lactose 
solid medium. 
Series V consisting of 1,728 colonies from 10 different 
samples of human feces showed only 69 that belong to the 
class of glucose+lactose.—This works out at about 4%, the 
remaining 96% being glucose+lactose+. A similar series 
(Series VI) was obtained from cowdung. Out of 80 colonies 
that were grown in glucose broth and separated out on a 
lactose medium, 4 belong to the class of glucose +lactose—. This 
is 5% of all colonies. 
