22 
These three experiments, as well as the following ones with sponge, 
show in a vei\v definite manner the effect of temperature on the hacillns 
pestis. The organism lived only a few days in the incubator at the 
body teni'perature, while it survived over four months in the cold — ■ 
17° to 19° C. 
Another series of infected sponge was exposed in order to verify the 
rather remarkable results obtained in Nos. 26, 27, and 28. The results 
obtained were about the same, so it is plain that when well protected 
in a porous material like sponge the plague bacillus may live and retain 
its virulence a long time, even when dry. 
No. 29. — Bouillon Culture on Sponge, 17° to 19° C. 
Time. 
Result. 
Remarks. 
3 days 
+ 
8 days 
+ 
14 days 
25 days 
The pieces of sponge are dry. 
35 days 
- 
46 days 
-L 
60 days 
1 
"T" 
70 days 
1 
T 
80 days 
“T 
0.5 c. c. of a bouillon culture killed 
mouse in 2 days. 
1 
97 days 
— 
106 days 
- 
1 
) 
116 days 
— 
: 
No. 30. — Bouillon Culture on Sponge, 22° to 29° C. 
Time. 
I 
Result. Remarks. i 
^ i ! 
3 days 
- 1 - ! 1 
8 days 
' ! 
14 days 
— ■ + 
25 days 
+ Killed a mouse in 4 days. 
35 days 
1 + 
46 days 
! — Contaminated. 
60 daj’s 
-i- I Failed to kill a mouse. j 
70 days 
+ I j 
80 days 
+ i 
97 days 
-.-.1 -f ! 
106 days 
- 1 
116 days 
i 
Another series of experiments with sponge was tried to determine 
the effects of moisture. A pledget of absorbent cotton saturated with 
water was kept in the Petri dish along with the test objects. It was 
found difficult to prevent contamination in the presence of moisture, 
and also difficult to keep the objects moist so long a time. 
