3 2 4 
Journal of Agricultural Research 
Vol. II, No. 4 
2. THE THERMAE DEATH POINT OF THE CUETURKS CEASSIFIED ACCORDING 
TO SOURCE 
In order to determine whether streptococci from certain sources 
were more resistant to heating than others, the cultures have been 
grouped according to their sources. As before stated, the streptococci 
used in this study were isolated from cow feces, from the mouth and 
udder of the cow, and from milk and cream. 
Table II shows that of the 45 cultures from cow feces, 44, or 97.77 
per cent, survived 57.2 0 C. (135 0 F.). At 62.8° C. (140° F.) 31, or 68.88 
per cent, survived. When heated to 62.8° C. (145 0 F.), 9 cultures, or 
20 per cent, withstood the temperature. At 65.5° C. (150° F.) only 
Fig. 2 .—Results of heating streptococci (classified according to source) for 30 minutes at various 
temperatures. 
4.44 per cent, survived, while at 68.3° C. (155^ F.) all the streptococci 
were killed. 
The cultures from the udder, as a whole, were less heat resistant than 
those from-feces, although a few were able to withstand high temperatures. 
Of the 40 cultures 60 per cent were able to survive heating to 57.2 0 C- 
(135 0 F.). At 6o° C. (140° F.) 45 per cent withstood the heating. At 
62.8° C. (145 0 F.) 17.50 per cent survived. When heated to 71.i° C. 
(160 0 F.), 1 culture, or 2.5 per cent, still survived, but all were destroyed 
at 73-9° C. (165° F.). 
In ability to withstand heat the streptococci from the mouth were 
very similar to those from feces. 
The cultures isolated from milk and cream, however, were much more 
heat resistant than those from the three other sources. At 6o° C. 
(140° F.) 18 cultures, or 100 per cent, survived. When heated at 62.8° C. 
(145 0 F.) 17, or 94.44 per cent, still survived. At 65.6° C. (150° F.) 
72.22 per cent withstood the heating. Even at a temperature as high as 
