i26 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
The various inoculated media were kept in a dark place at room temperature, 
and from day to day one c.c. undiluted, or diluted if necessary, was plated. After the 
colonies were counted, subcultures were made in Durham's fermentation tubes 
containing glucose broth. The following experiments are selected from a large 
number which gave similar results. 
The growth of the B. typhosus in ordinary flour was hard to estimate, owing 
to the overgrowth of contaminating organisms, but in one or two cases, where the 
contamination was of slight degree, results similar to those of Klein and Houston 
were obtained. 
Experiment r. Ten grammes of flour were weighed out, and 100 c.c. of 
sterilized water added. This was kept in a sterilized flask and inoculated with 
B. typhosus : — 
When cultures were 
maile 
Dilution 
No. of colonies 
on plate 
No. of bacteria per c.c. 
Immediately 
I : 100,000 
132 
I 3,200,000 
i day 
1 : 1, 000, coo 
2,226 
2,2 26,000,000 
4 days 
I : I, COO, COO 
I 
1 ,000,000 
5 days 
1 : 10,000 
O 
Less than 1 0,000 
7 days 
1 : 1 
O 
0 
8 days 
O 
0 
To avoid the difficulties caused by contamination, another series of experi- 
ments were undertaken to see if filtered solutions would give the same result. 
Experiment 2. A ten per cent, mixture of flour in sterilized water was made. 
This was filtered through a sterilized Pasteur-Chamberland filter and inoculated 
with B. typhosus : — 
When cultures were 
made 
Dilution 
No. of colonies on 
plate 
No. of bacteria per c.c. 
Immediately 
I : 10,000 
I,o8o 
I 0,8 JO, OOO 
I day 
I : 1 OO 
I 
IOO 
3 days 
1 : 1 
0 
O 
5 days 
1 : 1 
O 
O 
