106 
isms at most. times of the year renders their study extremely 
difficult, but the little we do know about them is based on 
sound evidence collected from Madras, Bengal, and the United 
Provinces. The facts may be recapitulated: in the great 
majority of cases it appears in feces during heavy monsoon 
weather, and at the same time it is to be isolated from water- 
supplies ; it is practically never found except when the water 
is very grossly polluted with fresh material, and it disappears 
with very great rapidity. It has not yet been definitely 
ascertained whether the organism is a true inhabitant of 
intestinal tracts of man and animals, or is just a passing 
guest. 
Bacillus Lactis Arogenes. 
Bacillus Lactis 7Zrogenes occupies a very extraordinary 
position in nature. First of all, it must be stated that the 
organism is rare in feces. One or two per cent. of all organ- 
isms isolated is about what one would expect. Up to the 
present no sudden prevalence of this organism has ever 
been found in feces, as has been recorded of certain other 
organisms. In grossly and recently polluted water lactis 
erogenes iS a rare organism, but usually within a period of 
about 5 to 15 days after pollution in lakes the organism 
becomes extremely common. 
Particular attention is directed to Chapter VIII where 
a study of the Red Hills Lake was discussed. There it has 
been shown on several occasions after pollution of a gross 
character, lactis erogenes is invariably very common some 
days after the pollution was added. Besides this the 
figures given in Chapter IX are in themselves absolutely 
indisputable. In rivers the period of time when rain 1s 
common is characterised by an enormous increase in the 
number of lactis wrogenes, and yet we are _ perfectly 
certain that the organism is rare in feces. Furthermore, 
the bacillus is not a very resistant one, because, as 
time goes on, if no further pollution is added, lactis 
erogenes disappears and gives place to the true resistant 
varieties. The figures already given are convincing as to 
