1917] DAIEY FARMING DAIRYING. 475 



clarified milk, and of the pasteurized milk, and two or three guinea pigs were 

 inoculated with the cream and sediment obtained by centrifuging each sample. 



Of the 24 samples of raw milk used all except one produced tuberculosis iu 

 the inoculated guinea pigs, and in this case both inoculated guinea pigs died 

 from septicemia. After clarification 14 samples of the same milk produced 

 tuberculosis in all of the inoculated guinea pigs in all but three cases, and in 

 one of these both inoculated guinea pigs died of septicemia. From the other 

 two samples one guinea pig in each case developed tuberculosis while the other 

 died soon after inoculation. After pasteurization 23 sample.s of the same milk 

 (plus the required amount of milk or cream to standardize the vat) failed to 

 produce tuberculosis or cause death from inoculation in a single instance. 

 Twelve of these samples were heated above 140° F. and held for a longer 

 period than 20 minutes. The remaining 11 were definitely known to be heated 

 to 140° and held for only 20 minutes. 



From these findings the authors conclude (1) that pasteurization at 140" 

 for 20 minutes kills tubercle bacilli in naturally infected milk, (2) that with a 

 properly insulated tank in whicli the heating and holding ai"e done in the same 

 tank, while the milk is being constantly agitated, one can produce and hold 

 the temperature of all the contained milk at the desired point and for the 

 df^sired length of time, and (3) that clarification of milk naturally infected with" 

 tubercle bacilli fails to render it innocuous to guinea pigs. 



In these tests it was found that tubercle bacilli were not destroyed in milk 

 samples preserved with 1 per cent boric acid. Such preservation was sufiicient 

 to allow samples to be shipped considerable distances without their undergoing 

 undesirable changes which interfere with laboratory examinations and guinea- 

 pig inoculations. 



Comparison of the rate of multiplication of bacteria in raw milk with the 

 rate in pasteurized milk, P. W. Allen (Jour. Infect. Diseases, 19 {1916), No. 

 5, pp. 121-128, figs. 1). — In the experiments reported aseptically drawn milk 

 was obtained from cows with a low udder bacterial content and 200-cc. samples 

 were measured out. One portion was pasteurized and the other was not. 

 After pasteurization the treatment of the two portions was the same. Parallel 

 samples in a part of the series were inoculated with Bacterium lactic acidi from 

 Ericsson's butter culture in sufficient quantities to mask the effect of the udder 

 organisms. Into each of the samples of the remaining series was inoculated 

 by means of a special pipette one chromogenic bacterium which, on account of 

 the extreme color, could be easily distinguished from the udder organsms. The 

 plate counts of the different samples are tabulated and graphs are given of 

 parallel samples of most of the series. 



It was found that raw milk, as compared with pasteurized milk, exerts a 

 powerful suppressing influence on the multiplication of certain bacteria. When 

 B. lactis acidi is accustomed to the milk of a certain cow, however, apparently 

 no killing off of this organism takes place in freshly drawn milk. When a 

 single cell of certain pronouncedly chromogenic kinds of bacteria is added to 

 fresh milk, the organism is found plentifully in the milk after 16 hours at 20° C, 

 the injurious action of freshly drawn milk not being sufficiently intense to kill 

 the one bacterial cell. After pasteurization, the organisms which remain in the 

 milk and those which are able to get into it find conditions more favorable for 

 their rapid multiplication than before pasteurization. 



The relation of lactic acid bacteria to milk of different degrees of fresh- 

 ness, A. VoiTKEVicH (A. WojTKiEwicz) (Vtesttiik Bakt. Agron. Sta. V. K. 

 Ferrein, No. 22 (1916), pp. 55-19). — The author takes exception to the conclu- 

 sions of Paraschtschuk (E. S. R., 31, p. 506) that certain species of lactic-acid 

 bacteria develop more rapidly in fresh milk than in milk which is not fresh. 



