no THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
Experiment 4. Isolation of B. typhosus from infected milk 
A flask containing 200 c.c. of milk was inoculated with one loop of a twenty- 
eight hour bouillon culture of B. typhosus, and well shaken. Small quantities were 
introduced into tubes as in the case of the water ; the tubes were filled with bile-salt 
gelatin and placed in the thermostat ; cultures were made at intervals, with the results 
shown in Table 3. 
TABLE 3 
Showing the results of an experiment to detect, by the use of gelatin tubes, 
typhoid bacilli in infected milk: — 
Tube 
Amount inoculated at bottom 
Plates made from surface of gelatin 
of tube 
At start 
After 2 hours 
After 22 hours 
N 
C05 C.C. 
Sterile 
Sterile 
Pure culture 
B. typhosus 
O 
cri c.c. 
do. 
do. 
do. 
P 
0"2 c.c. 
do. 
do. 
do. 
Q 
c-5 c.c. 
do. 
do. 
do. 
R 
ro c.c. 
do. 
do. 
do. 
S 
2'0 C.C 
do. 
Pure culture 
B. typhosus 
do. 
PRELIMINARY EXPERIMENT ON A METHOD FOR INCREASING 
THE NUMBER OF TYPHOID BACILLI IN A FLUID SUSPECTED 
OF CONTAMINATION 
Four factors have been generally recognized as hindering the detection of 
B. typhosus in water, viz. : — (1) The comparatively small number present. (2) The 
lack of nutrition suitable to keep the organisms alive during the period of investi- 
gation. (3) The presence of B. coli. (4) The presence of other bacteria, chiefly 
saprophytes. 
The previous experiment had led one to believe that under suitable conditions 
B. typhosus was not overgrown by B. coli. It was hoped, moreover, by the use of 
bile-salt and a high temperature to inhibit the growth of non-intestinal organisms in 
the water under examination. Two of the difficulties were thus met, theoretically at 
least. A suggestion recently made by Savage 9 led one to believe that the nutrition 
could be provided for ; and finally, a knowledge of the method recommended by 
