128 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
Experiment 5 
When cultures were 
made 
Dilution 
No. of colonies on 
plate 
No. of bacteria per 
c.c. 
Immediately 
I : I 
00 
2 days 
1 : 1 
O 
4. days 
1 : 1 
O 
5 days 
1 : 1 
O 
These results appear to disprove that the bactericidal power, if it exists, is 
destroyed by heating. 
A preliminary analysis of these media gave the following reactions : — 
On heating, a light precipitate was thrown down. 
Acidity 10 c.c. = otc c.c. - NaOH. 
j j 10 
Fehling's test showed a trace of a reducing substance present. 
Biuret reaction showed the presence of proteid. 
A precipitate was obtained by saturating some of the solution with ammonium 
sulphate. This precipitate was washed and dissolved in sterilized water. 
The solution so obtained was inoculated with B. typhosus. The bacillus dis- 
appeared in from eight to nine days, thus showing no special bactericidal effect. Two 
experiments were made with potato juice filtered through a sterilized filter and inocu- 
lated with B. typhosus. One was heated to boiling before inoculation. In both these 
the growth was very luxuriant after eighteen days, when the material was exhausted. 
Similarly, apple juice had no bactericidal effect. 
As a control, a series of experiments were made by inoculating B. typhosus into 
sterilized tap water. 
Experiment 6. Sterilized water inoculated with B. typhsous. 
When cultures were 
made 
Dilution 
No. of colonies on 
plate 
No. of bacteria per 
c.c. 
Immediately 
1 : 100 
yz> 
00 
1 day 
1 : 100 
17 
1,700 
3 days 
1 : 1 
cc 
00 
5 days 
1 : 1 
I 2 
I 2 
6 days 
1 : 1 
IO 
I 0 
7 days 
1 : 1 
5 
5 
8 days 
1 : 1 
0 
0 
10 days 
1 : 1 
0 
0 
