64 
of sunlight, there are some which appear to be very resistant, 
and there is a third group which may be called intermediate 
between the two extremes. 
It should be explained that the reasons for working with 
emulsions of fresh human and animal feces were that from a 
series of experiments carried out on laboratory cultures, we 
find that these latter behave in an entirely different way from 
the organisms obtained direct from the intestinal tracts of 
man and animals. It soon became apparent that any con- 
clusions which applied to fresh faeces did not necessarily apply 
to laboratory cultures of the same organism. This, of course, 
may be brought forward as an objection to this form of 
experiment. 
Let us now give the details of the experiments carried 
out. In the first instance we attempted to show that by 
placing a mixture, such as the one described above, in the sun 
and protecting it from outside contamination that bacilli 
present actually decrease in numbers fairly rapidly. This 
was not by any means a difficult point to prove, and all our 
experiments showed that this disappearance was fairly con- 
sistent and rapid. One experiment, Table No. VII (a), is given 
as an example for the rest, there being no necessity to describe 
in detail every separate experiment. 
Having established the fact that fecal organisms placed 
in water in the sun do disappear, we went a step further 
in order to ascertain whether there was any difference in the 
rapidity with which the separate species of organisms vanish. 
About 50 such experiments on this line have been carried 
out, to of the most typical of these have been selected and 
given in detail below. Selecting experiments may be open 
to objection, but it is needless to give details of all those 
carried ‘out, many of them are not of much value because 
susceptible and resistant organisms were not present in the 
original emulsion. 
Before giving the actual results of these experiments it 
is necessary to make a few comments. 
In all bacteriological work the method chosen has its 
own limitations; that followed by us is no exception to the 
rule. Although Io colonies, all of which are carefully sub- 
