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into. At present it is temporarily placed in class III, 
amongst the resistant organisms. The fact that it is some- 
what rare renders it difficult to put into its proper place 
without more work. 
Bacillus Nos. 100 and to1.—This is an organism about 
which we were at first inclined to be sceptical, in spite of the 
fact that several bacteriologists claim to have isolated it. 
It is nearly always found in mixtures with lactis zrogenes, 
and the difference between these two bacteria is mainly the 
presence or absence of Vosges and Proskauer’s reaction. 
There is no doubt that it is a separate organism. It is met 
with in the feces of both man and cattle, but more fre- 
quently in the latter. At the same time there is also no doubt 
that attenuated specimens of lactis zrogenes lose their power 
of giving the Vosges and Proskauer’s reaction ; so when both 
organisms are found together in a water we look on it as 
probably being lactis zrogenes. 
Coscoroba or No. 106.—This organism, next to the Grunthal 
group, has been found by us to be the commonest in the feces 
of man and domestic animals. As the analyses show, its 
frequency varies greatly at different times of the year. It is 
very common in water, particularly in such water as we are 
certain is derived from washing the surface of a polluted 
ground. It has not been found common ,in the samples of 
earth we have taken. It is doubtful if this bacterium should . 
not be in class III. 
Bacillus P.—Although organism P. is not a lactose fer- 
menter, it must be considered along with the others. First of 
all the reason we have named it organism P. is because at one 
time we thought it was almost identical with the ordinary 
sewage Proteus, but on further investigation it is found to 
differ very considerably from the classical organisms which 
have been described by many bacteriologists. On finding 
that the organism was not sewage Proteus, we still wrote 
it in our laboratory returns as bacillus P. 
There is no doubt, whatever, that this is by far the com- 
monest organism of feecal origin in ordinary surface waters. 
As already pointed out it is quite rare in fresh feces, but 
there is no doubt that it multiplies in water in spite of the 
