426 



C. M. HILLIARD AND MILDRED A, DAVIS 



increases slightly the germicidal activity, (e) and the fact that 

 cream and milk furnish some protection to bacteria frozen in 

 them either continuously or intermittently. 



We were most interested to learn, if possible, whether some 

 external factor, other than the low temperature, entered into the 



TABLE 2 



A comparison of the percentage reduction of B. coli held at 0.5°C., —15°C., and 

 frozen intermittently in tap water for a three hour period 



TABLE 3 

 Percentage reduction obtained with B. coli in cream at freezing temperatures 



destruction of the bacteria. Is there a critical degree of cold 

 at, or, just below, freezing which is highly fatal, or is the crystal- 

 lizing action itself destructive? We have noted the conclusion 

 of Prudden, where cold itself was chiefly emphasized. Keith 

 emphasized the solidification. Most work on cold has been 



