DISTRIBUTION OF BACTERIUM COLI COMMUNE 
5 
B. coli, in broth or peptone-salt solution, were diluted with sterile tap-water (i in 
1,000,000 or 1 in 10,000,000) and plates made of 1 c.c. Comparison was made with 
ordinary agar, and it was found that, when freshly made dilutions of fresh cultures 
were used, there was no diminution in numbers on the carbolized medium (Experiments 
1, 5, 6, Table II). In Experiment 4 an old culture was used, and in Experiments 2 
and 3 old dilutions were used. In this latter case the numbers of B. coli, counted on 
ordinary agar, decreased in the dilution from 3,505 per c.c, on the day the dilution 
was made, to 500 two days later, and to 81 at the end of three days. At the same 
time there was great diminution in the numbers on carbolized agar as compared with 
those on ordinary agar. It would seem as though — the vitality of the bacillus being 
lowered by remaining so long in water — it was unable to withstand the carbolized 
medium. This method, then, gives the number of robust individuals rather than the 
total number ; this, I think, is a point in its favour. It may also be seen from 
TABLE II 
ment 
No. 
Date 
Description of culture anil dilution 
Temperature 
f No. of 
colonies on 
ordinary agar 
plates 
t No. of 
colonies on 
carbolized 
agar plates 
I 
March 24, 
48 hrs. culture of B. coli 
*37° C 
35°5^ 
5307 
IQOO 
commune, diluted 
1 in 1,000,000, sterile water 
* + 2° C. 
3187 
2790 
and 1 c.c. taken 
2 
March 26, 
Dilution of Experiment 1, 
37° C. 
2 
1900 
diluted yet 1 in 100, 
and I c.c. taken 
42° C. 
2 
O 
3 
March 27, 
Dilution of Experiment 
37° C. 
81 
30 
1900 
I used 
+2' C. 
61 
3 
4 
March 28, 
8 days peptone-salt cul- 
37° 
5 
1900 
ture, diluted 1 in 
10,000,000, and 1 c.c. 
42 0 
16 
4 
taken 
5 
April 6, 
24 hrs. broth culture, 
37° 
469 
585 
1900 
diluted 1 in 10,000,000, 
42 0 
438 
422 
and 1 c.c. taken 
20° 
(1)3 days incub 
455 
0 
(2)4daysincub. 
5°5 
4° 3 
6 
April 7, 
24 hrs. broth culture, 
37° 
89 
104 
1900 
diluted 1 in 100,000,000, 
42 °o 
114 
119 
and 1 c.c. taken 
20 
(1) 3 days 
H7 
0 
(2)23 days 
157 
84 
* All plates incubated at 37 0 or 42° were counted after f Numbers refer to the mean of three enumerations in 
48 hrs. incubation. each case. 
