49
In the light of these remarks nothing more need be said on the utility of attempt-
ing to establish an approximate percentage composition of the intestinal bacilli in the
dejecta of different animals. Even the percentages in the four large groups, described.
by MacConkey, are so variable that only the vaguest generalizations are possible.
There is one other point we wish to allude to. Our experience in all the work
on faces in this and other parts of this report (particularly in Chapter VIII, on the
Effects of Sunlight on Fœcal Organisms) shows, that we have never found any fœcal
organism special to the intestinal tract of either man, cows or goats. It is true that
a very few rue organisms, found in cowdung, have not yet been isolated from human
fœces, but it is probably only a case of time until they will be found to be present
there also. On the other hand, we have not isolated a single organism from human
faces,, that has not been found in cowdung at one time or another. For some time we
thought organism No. 33 was confined to the intestinal tract of man, but it was
eventually obtained from eowdung. Not only is it true that " at present there is
no means of differentiating the lactose fermenting organisms of human from those of
animal origin" (MacConkey, 1905) ; but there is probably not a single lactose
fermenting organism that is peculiar to any given animal.
More work is required on this very interesting subject of bacteria in fœces ; at
present we can only be said to have pointed out a few leading lines, and to have
discovered certain problems, the explanation of which, we are, at this stage, entirely
ignorant of. We consider the following wide conclusions are justifiable:-
(1) That, the flora of the intestinal tracts of men and animals are subject to
very considerable changes due to influence which are at present unknown. These
influences have been proved to operate over very wide areas.
,(2) That, within certain very wide limits, these forces appear to affect man
and animals equally, both as regards number and kind of micro-organisms.
(3) That, under well defined conditions, such as heavy rainfall, the water-
supplies contain the same organisms as the feces of man and animals at that parti-
cular time ; but that this similarity of bacteriological flora is. also noticed occasionally
when rain is absent and there is now apparent cause for it. The explanation of this
occurrence is at present unknown.
(4) That, having regard to the variation in the bacteria in fœces, both in
quantity and kind, no constant approximate composition can be arrived at. Even in
the large groups, suggested by MacConkey, variation in percentage composition in
the same animal is considerable.
(5) No lactose fermenting organism has been isolated by us that has been
proved to be the inhabitant of the intestinal tract of cattle or man only.
(6) That the numerical relation of the organisms constituting MacConkey's
groups in the intestines of cattle in India is entirely different from that in England ;
while in the intestines of man it appears to be very similar in the two countries.
(7) That, a study of the organisms present in fœces at different times of the
year is necessary for the proper interpretation of the results obtained from water
analyses.