61 
Experiment Xo. 21, 
B. diphtheriae. 
Culture, “Park, Xo. 8;” seventy-two hours’ growth in sterilized milk. Reaction 
of milk, 0.18 per cent acid. 
The milk at 24° C. immersed in constant-temperature water bath at 55° C. 
At start 
11 minutes after immersion 
If minutes after immersion 
2J minutes after immersion 
2f minutes after immersion 
31 minutes after immersion 
4 minutes after immersion . 
51 minutes after immersion. 
61 minutes after immersion. 
71 minutes after immersion. 
Milk culture. 
Temper- 
ature 
(°C.). 
0.5 c. c. milk cul- 
ture in bouillon. 
24 
GrouTh. 
45 
Do. 
50 
Do. 
55 
Do. 
57 
No gro^\*th. 
58 
Do. 
59 
Do. 
60 
Do. 
60.4 
Do. 
60.5 
Do. 
Experiment Xo. 22. 
B. diphtheriae. 
Culture, “Park, Xo. 8;” forty-eight hours’ growth in whole milk that had been 
sterilized by the fractional method three days. Reaction, 0.216 per cent acid. 
The milk at 21° C. immersed in constant-temperature water bath at 60° C. 
Milk culture. 
Temperature (° C.). 
1 c. c. milk cul- 
ture in bouillon. 
At start 
11 minutes after immersion 
2 minutes after immersion . 
21 minutes after immersion , 
2| minutes after immersion . 
3f minutes after immersion 
5 minutes after immersion . 
6 minutes after immersion . 
7 minutes after immersion . 
8 minutes after immersion . 
21 
Growth. 
50 
Do. 
53 
Do. 
i 55 
No growth. 
! 57 
Do. 
' 59 
60 
.... Do. 
1 minute at 60 
Do. 
2 minutes at 60 
Do: 
3 minutes at 60 
Do. 
Conclusion . — The diphtheria bacilli succumb at comparatively low 
temperatures. Oftentimes they fail to grow after heating to 55° C. 
Some occasional!}^ survive until the milk reaches 60° C. 
