528 WILLIAM H. CHAMBERS 



tures. Stocking explains the reduction in the number of bac- 

 teria in the mixed milk from a herd of thirty cows as due to the 

 death of those organisms which find milk an unfavorable medium 

 while a parallel increase of lactic acid forms is taking place; but 

 he makes no comparison of the behavior of the first group in raw 

 and heated milk to show that the decrease is not due to a prop- 

 erty of raw milk only. The relationship between germicidal 

 action and temperature has been demonstrated by Koning, Hun- 

 ziker, and others. Pure culture work from 1905 to 1909 by Hip- 

 pius, Coplans, Brudny, Evans and Cope, Heinemann, and Rose- 

 nau has shown a definite germicidal action in varying degrees 

 on quite a number of different species of bacteria, but the possi- 

 bility of variation in individual cows is practically ignored and 

 their conclusions are based on the action of only one or two cows. 

 Heinemann found agglutinins for certain bacteria in milk serum 

 and concluded that they seemed to bear some relation to the 

 germicidal action. On assembling the work of the different in- 

 vestigators, it appears that much of the variation in results is 

 due to a lack of consideration, in each case, of one or more of the 

 essential factors. 



It is the endeavor of this experimental work to correlate the 

 important factors, emphasizing the individuality of the cow and 

 the specificity of action of the bacteria, and by direct microscopic 

 examination of the milk which is being tested to follow the growth 

 of the bacteria and observe any evidence of agglutination. The 

 milk was obtained from eleven cows from the University of Illi- 

 nois herd, selected because in previous experiments they had 

 shown a low germ content in the udder. Three organisms were 

 used for inoculation in pure culture: Bad. coli, Bad. ladis-acidi, 

 and a brilliant red chromogen isolated from a creamery can and 

 designated Culture R. Near the middle of the milking, about 1 

 pint of milk, in approximately equal portions from each quarter 

 of the udder, was drawn with aseptic precautions into a small 

 sterile container. One half, to be inoculated raw, was held at 

 37°C, while the other half was heated to between 85°C. and 

 90°C. for two minutes and then cooled to 37°C. Ninety-nine 

 cubic centimeter portions of the raw and heated milk in 300 cc. 



