SIGNIFICANCE OP COLON COUNT IN MILK. 



19 



Table 10. — Number of organisms of colon-aerogenes group introduced into fresh milk 



under abnormal conditions. 



Conditions. 



Sample 

 No. 



Total 

 count. 



Colon 

 count. 







Per c. c. 



Per c. c. 





( 1 



18, 900, 000 



5,200,000 





2 



25,300,000 



3,600,000 





3 



16,500,000 



1,190,000 





4 



22, 700, 000 



5, 100, 000 



Utensils held 24 hours before washing; not sterilized. August 21 to 30, 



5 



g 



28,200,000 

 33,000,000 

 17,200,000 



6, 700, 000 



1,620,000 



340,000 



and September 8 to 17; air temperature 70° F. to 98° F. (21.1° C. to 

 37 5° C) 



7 





8 



33, 500, 000 



690, 000 





9 



54,000,000 



1,780,000 





10 



65, 000, 000 



2,350,000 





il 



25, 000, 000 



1, 190, 000 





I 12 



2, 040, 000 



80,000 





1 



2,050,000 



91,000 





2 



2,800,000 



72,000 





October 3 to 12, 

 75° F. (23.9° C). 



3 



4 

 5 



2,320,000 



2,210,000 



680,000 



120,000 



350,000 



1,400 







6 



450,000 



5,200 







7 



365, 000 



4,500 







1 



1,010,000 



0) 





October 22 to 25, 



2 



3*0,000 



200 





60°F.(21.1°C.). 



3 



690,000 



100 







4 



580,000 



300 







1 



270,000 



1,400 



Utensils held 24hours before washing; not sterilized. 



October 22 to 25, 

 75° F. (23.9° O). 



2 

 3 



560,000 

 370,000 



500 

 300 







4 



490,000 



400 







1 



163,000 



1,200 





October 29 to No- 



2 



490,000 



2,200 





vember 5, 60° 



3 



410,000 



800 





F. (21.1° C.).... 



4 



288,000 



700 







5 



310,000 



100 







1 



1, 100, 000 



37,000 





October 29 to No- 



2 



225,000 



13,000 





vember 5, 86° 



3 



98,000 



400 





F. (30° C.) 



4 



161,000 



300 





5 



42,000 



200 



» in 1/100 c. c. 



These results indicate that under abnormal conditions the colon 

 <;ount may be over 2,000 per cubic centimeter in fresh milk, but it is 

 believed, in view of our experiments, that such exceptional condi- 

 tions are seldom encountered. These high counts therefore do not 

 detract from the value of the 2,000 maximum colon count per cubic 

 centimeter, which has been set as the maximum contamination by 

 organisms of the colon-aerogenes group in fresh milk. 



WHY ARE HIGH COLON COUNTS OFTEN FOUND IN RAW MILK? 



Assuming the correctness of the fact just established that fresh 

 milk produced under normal conditions very rarely contains over 

 2,000 organisms of the colon-aerogenes group per cubic centimeter, 

 the question "Why are high colon counts often found in raw milk?" 

 can be answered by the statement that high colon counts in raw milk 

 are due to growth which takes place between the time of production 

 and that of consumption. 



If organisms of the colon-aerogenes group were not able to grow in 

 milk the colon count would be of far greater value as an index of con- 



