FORTY-THIRD ANNUAL CONVENTION 63 



According to this, you see. there is a new generation every 

 fifteen minutes under favorable condition. You have practically 

 all the favorable conditions present when you have an open pail 

 of warm milk in a dirty barn. 



This next slide is a table showing numerically the differ- 

 ence in the speed with wdiich bacteria grow at a favorable tem- 

 perature and at an unfavorable one : — 



Slide — Rapidity w^ith which bacteria multiply in milk. 



Temp. o hrs. 6 hrs. 12 hrs. 24 hrs. 40 hrs. 



50° 10 J2 15 41 62 



68° 10 17 242 61,280 3,574,990 



We are assuming here that we started with the same num- 

 ber of bacteria in each sample. At the end of 40 hours the one 

 kept at 50° F. would only have 62 bacteria while the sample kept 

 at 68° F. would have over 3 million. 



This slide shows the effect of poor cooling of milk while ii 

 is kept at the farm. Each line represents two samples of milk 

 taken from the same farmer's cans, one being taken from a can 

 of morning's milk, and the other from a can of milk held from 

 the previous evening, not properly cooled. As you see, in aU 

 cases the p. m. or evening's milk contained many more bacteria 

 than the morning's milk. 



Slide — Poor Cooling. 



P. M. Milk. A. M. Milk. 

 5,900,000 30,000 



16,700,000 70,000 



1,300,000 90,000 



2,000,000 6o,OOG 



3,200,000 120,000 



230,000 40,000 



The next slide shows the number of bacteria, per cubic 

 centimeter (about 1-4 teaspoonful), found in the milk of -a cer- 

 tain dairyman at the time it was milked, and on the sgme line 

 the number of bacteria found in a similar amount of the same 

 milk when taken out on the dairyman's route the next morning 

 after having been held over night and bottled. 



