TEMPERATURE AND B. COLI 



139 



the B. coli content of milk must be regarded as due more to 

 reproduction than to original contamination. Diagram No. 

 Ill, which shows the B. coli content of the Ottawa raw milk 

 supply compared with the mean atmospheric temperature, 

 demonstrates very clearly the effect of temperature. In the 

 autimin months the curves do not correspond because the mode 

 of the B. coH curve is lowered during the hot summer months 



Diagram No. Ill 



EFFECT OF ATMOSPHERIC TEMPERATURE ON B. COLI CONTENT 

 OTTAWA 



18,000 

 16,000 

 14,000 



g 12,000 



V ■ 



u 

 010,000 



o 



^ 8,000 



6,000 



4,000 



2.000 



n 



90 



a 

 70 «w 



XI 

 fM 



60 £ 



50 2 



a 



2 



40 ^ 



a 



by artificial cooling of the milk and the temperature of the milk 

 is, consequently, not proportional to the atmospheric, but it is 

 evident that artificial cooling is abandoned before the natural 

 agencies become entirely operative. It is also interesting to 

 note that after the very cold winter weather the B. coli content 

 does not increase until the mean atmospheric temperature 

 exceeds the critical temperature. 



