76 
Experiment No. to—Contd. 
The water before exposure contained .. 1 lactis erogenes, 2 coscoroba, 1 
neapolitanus, I cloace, 2 acidi 
lactici, 3 Grunthal. 
After 1 hour’s S exposure showed -- 2lactis wrogenes, 2 ¢l@aceaas 
neapolitanus, I coscoroba, 3 
Grunthal, 1 No. 101. 
»» 2 hours’ rd f .. 3lactis w#rogenes, 6 coscoroba, I 
Grunthal. 
“s bs .. IJactis zwrogenés, 3 No. (Gpguae 
Grunthal. 
. a $e .. 2 lactis erogenes, 3 cloacz, 5 No. 67. 
i =, do Ne: to, 
oe . 5 .« «9 cloaczear Ne67: 
5 : ; 
Noon of the second day (after 12 hours’ exposure) sterile, no lactose 
fermenters. 
Ww 
oun BB 
Note.—The original water is very rich in different species ; persistence 
of lactis erogenes till near the end ; appearance of organism No. 67 and _ parti- 
cularly No. ror late on in the exposure ; final survival of cloace. 
Now when an emulsion very rich in fecal organisms is 
exposed to the sun, within the first hour or two (according to 
the clearness of the liquor, and the power of the sun), a very 
large number of these bacilli die off, and the more resistant 
organisms begin to appear in the test portions. It must be 
carefully understood that if the organisms A., B., C. (A. being a 
delicate organism, B. one of medium resisting power and Ca 
a resistant one) be exposed to the sun, it is not maintained 
that all the A’s must disappear before any of the B’s begin 
to die, or that the whole lot of organism B. must have been 
killed before any of C. die off. There must be a great deal 
of overlapping, especially among organisms whose power of 
resistance is nearly equal. Again if 100 pure cultures of A. 
B. and C. were all exposed to the sun under similar circum- 
stances, it Is not maintained that all the A’s would die out 
before any of the B’s or C’s. In a hundred such cultures, 
from different strains, a proportion of the B’s might die off 
betore all the A’s were extinct ; yet the conclusion to be drawn 
from the whole experiment would not be altered very mater- 
ially, viz., that the majority of A. was more susceptible to 
the influence of the sun than the majority of B. and C. If, 
however, two very extreme cases were taken, such as a very 
