55
The next series of experiments that were carried out were performed on somewhat
similar lines. Four cc. of cowdung or human fœces were mixed with 3 litres of water,
and exposed in the usual way, care being taken to render the conditions of each experi--
ment as nearly alike as possible. In this case samples were taken at various intervals,
the number of organisms estimated so as to show the actual falling off in the numbers.
Thus to 3 tubes .001 of a cc., .03 tubes .01 of a cc., to 3 tubes .1 cc., to 3 tubes
1 cc., to 3 or 4 tubes 5 cc., to 2 tubes 10 cc., and to 1 tube 20 cc. of the
emulsion were added to bile salt lactose broth at various intervals. Consequently,
these experiments demonstrate the actual rapidity with which the bacilli disappeared.
In order to keep the experiments uniform with those of the earlier series, the larger
particles of the cowdung or the human fœces were not filtered off, the whole emul-
sion being placed. out in the sun this accounts for the various irregularities in the
results obtained. When a sample was to be taken, the same arrangements previously
described were adopted, viz., the whole contents of the tray was well stirred up, the
..grosser particles allowed to subside for a few minutes, and the simple taken from the
clear fluid. Obviously, in a rough method of this kind, minute particles of fœcal matter,
to which bacilli would remain attached, were not infrequently included in the samples
taken, so that a perfectly regular filling off in the number of organisms was not
observed. The experiments, however, demonstrate without any doubt, the action of the
sun's rays in reducing the number of organisms. The rapidity with which sunlight
acts on any given mixture naturally varies with many factors, such as the colour of the
emulsion, the presence or otherwise of clouds in the sky, and very likely, the different
varieties of bacilli present in the emulsion itself. The results of experiments
Nos. 9, 10, 11, 12, 13, 14 and 15 are given in tabular form. The date, the hour and
the number of tubes inoculated with the amount of emulsion added to each is clearly
shown. Experiments Nos. 9, 10, 11 and 12 are the results of the action of sun's rays
on an emulsion of cowdung. This method of illustrating the results renders it
unnecessary to say more about these experiments. The falling off in the organisms is
well marked particularly in sample No. 10, where, but for the fact, that, in two
particular samples a large quantity of sediment was purposely included, the falling off
in the number of organisms is remarkably even.
TABLE VIII (c).
Experiments. .00
01
cc.
'001 cc.
01. cc.
.1 cc.
1 cc.
5 cc.
10 cc.
2 0
c c .
Remarks.
Experiment No. 13—Human
Fœces.
17-3-1909, noon before exposure + + + + + + + + + + + +
1 p.m. 1 hr. exposure
----- + + + + + + + + + +
2 p m. 2 hr.
do. ...
3 p.m. 3 hr.
do. ...
5 p.m. 5 hr.
do. ...
18-3-1909,12 noon
...
...
5 p m. ...
...
...
_ _ _
Experiment No. 14—Human
F œ c e s .
18-3-1909. noon before exposure.
+ + + + + + + + +
1. p.m. 1 hr.
do. ...
- - + + + + + + +
2 p.m. 2 hr. do. ...
+ + + + + + + + + + + + +
3 p.m. 3 hr. do. ...
- - - - - - -
+ + +
19-3-1909,2 p.m.
...
- -
5 p.m.
...
...
-
- -
Experiment No. 15—Human
F œ c e s .
21-3-1909,12-30 before exposure. - - - + + + + + +
1-30 1 hr.
do
3 p.m. 2 1/3 hr. do.
- - - -------
+
5 p.m. 4 1/3 hr. do.
22-3-1909, 1 p.m.
..
+ -
5 p.m.
...
-
- - -
- -
In the experiments with human fœces, we discovered. an interesting fact, viz., that
on account of the large amount of mucus present in this material, there was present in