26 



BULLETIN 739, U. S. DEPARTMENT OF AGRICULTURE. 



Table 14. — Influence of conditions of production on the subsequent increase of organisms 

 of the colon-aerogenes group — Continued. 







Total 



Colon count. 













Sample 

 No. 



Conditions. 



count in 

 fresh 





Held 6 



Held 24 hours at — 







milk. 



Fresh. 



hours at 

 86° F. 

 (30° C). 





















50° F. 

 (10° C). 



86° F. 

 (30° C). 



1 





( 670, 000 



100 



200 







260,000,000 



2 





820,000 







2,100 



100 



117,000,000 



3 





3,300,000 



1,200 



35,200 



1,400 



342,000,000 



4 





1,800,000 



100 



3,100 



200 



240,000,000 



5 





1,170,000 







400 







181,000,000 



6 





1,440,000 







700 



200 



159,000,000 



7 





620,000 



100 



0) 



300 



1,850,000 



8 





860,000 



300 



p) 



500 



194,000,000 



9 

 10 



11 



Barn dirty, cleaned twice a week; 

 • utensils washed after 8 hours but not 

 sterilized. 



570,000 



630,000 



1,300,000 



800 



• 300 



600 



1,500 

 9,700 

 1,400 



S) 



800 



120,000,000 

 162,000,000 

 72,000,000 



12 



2,720,000 



1,800 



510, 000 



3,300 



285,000,000 



13 





1,120,000 







600 







96,000,000 



14 





1,840,000 



900 



14,200 



1,200 



330,000,000 



15 





1,080,000 



1,100 



4,500 



1,500 



460,000,000 



16 





1,920,000 



1,300 



4,300 



2,700 



370,000,000 



17 





1,160,000 



100 



100 



1,300 



160,000,000 



18 





3,820,000, 



1,100 



12,400 



21,000 



196,000,000 



19 





2,200,000 



600 



CO 



P) 



115,000,000 



20 



• 



. 4,300,000 



1,500 



P) 



P) 



220,000,000 



Avt 



rage 



1,667,000 



595 



37,525 



2,156 



204,875,000 





i No determinations made. 



The results of these experiments in general confirm the opinion of 

 Race (13) that organisms of the colon-aerogenes group do not grow 

 at 45° F. (7.2° C), for as a rule little or no growth was found to take 

 place when milk was held at 50° F. (10° C.) for lengths of time com- 

 parable with commercial practice. 



In studying the growth of organisms of the colon-aerogenes group 

 in milk held at different temperatures, jfa of a cubic centimeter 

 was the largest quantity of milk examined, so that any growth 

 occurring in quantities less than 100 per cubic centimeter would not 

 have been detected. The results obtained therefore do not conflict 

 with those of Prescott (12), who found that milk which showed no 

 colon bacilli in a single cubic centimeter when fresh, after 24 hours 

 at 50° F. (10° C.) contained from 10 to 50 per cubic centimeter. 



When milk is kept at temperatures above 50° F. (10° C.) there 

 is a rapid growth of organisms in the colon-aerogenes group in direct 

 proportion to the temperature and time to which milk might be sub- 

 jected under commercial conditions. 



