SIGNIFICANCE OF COLON COUNT IN MILK. 



21 



cubic centimeter of milk and their average counts are given, together 

 with the per cent of samples which did not show the colon-aerogenes 

 group in this quantity of milk. Where more than one sample of a 

 group showed colon organisms the range is also given. The colon 

 counts represent the highest number determined on either litmus- 

 lactose-asparagin agar or on Endo medium. 



Table 11. — Growth and frequency of organisms of colon-aerogenes group at 50° F. (10° C.) 



Num- 

 ber of 







Average 

 total 



Colon count. 



sam- 

 ples. 





count. 



Fresh. 



24 hours. 



20 



Barn clean, cows clean, 

 utensils sterilized 

 (A). 



Per c. c. 

 4,245 



Per c. c. 

 100 per cent— in 1/100 c. c. 



Per c. c. 

 94.4 per cent— . 

 5.6 per cent+. 

 Average colon count, 300. 1 



34 



Barn dirty, cleaned 

 once a week; cows 

 dirty; utensils steril- 

 ized (B). 



38,262 



94.1 percent—. 

 5.9 per cent-K 

 Range, 100 to 300. 

 Average colon count, 200. 



100 per cent—. 



23 



Same as B, but uten- 

 sils not sterilized. 



161,083 



95.6 per cent—. 

 4.4 per cent+. 

 Average colon count, 400. 



100 per cent—. 



Num- 

 ber of 



Conditions. 



Average 

 total 

 count. 



Colon count. 



sam- 

 ples. 



48 hours. 



72 hours. 



96 hours. 



20 



Barn clean, cows 

 clean ; utensils 

 sterilized (A). 



Per c. c. 

 4,245 



Per c. c. 

 94.4 per cent—. 

 5.6 per cent+. 

 Average colon count, 

 3,200. 



Per c. c. 

 83.3 per cent—. 

 16.7 per cent+. 

 Range,l,600to28,000. 

 Average colon count, 

 10,533. 



Per c. c. 

 83.3 percent—. 

 16.7 per cent+ . 

 Range, 1,600 to 79,000. 

 Average colon count, 

 27,533. 



34 



Barn dirty,cleaned 

 once a week; cows 

 dirty; utensils 

 sterilized (B). 



38,262 



95.6 per cent—. 

 4.4 per cent+. 

 Average colon count, 

 1,900. 



95.6 per cent—. 

 4.4 per cent+. 

 Average colon count, 

 3,200. 



54.2 per cent—. 

 45.8 per cent+. 

 Range, 2.000 to 



186,000. 

 Average colon count, 



24,172. 



23 



Same as B,but uten- 

 sils not sterilized. 



161,083 



94.7 per cent—. 

 5.3 per cent+. 

 Average colon count, 

 11,600. 



83.3 per cent—. 

 16.7 per cent+. 

 Range,4,500 to 12,500. 

 Average colon count, 

 8,100. 



55.5 per cent—. 

 44.5 per cent 4-. 

 Range,3,300 to 22,000. 

 Average colon count, 

 13,300. 



1 Average colon count per cubic centimeter in samples showing them in ^ of a cubic centimeter and over. 



The average total count of 20 samples of milk produced under 

 clean conditions was 4,245, indicating a high quality of milk, from a 

 bacterial standpoint. No organisms of the colon-aerogenes group 

 were found in 1/100 of a cubic centimeter in any of these samples 

 when fresh. After 24 hours 94.4 per cent of the samples were still 

 negative, while 5.6 per cent were positive. The same results were 

 obtained at the end of 48 hours, only one sample showing organisms of 



