DAIRY FARMINC- — DAIRYING. 775 



rare an<l hMndlinp of (.-ream. The i>roce«lure under the State laws relative tn 

 licenses, examinations, and inspections is als) explained. 



The encouragement of clean milk production, L. li. Cook (Mdfts-. Bd. A(/r. 

 Circ. ,"W (HUo), pp. 9). — The author contends that the pnKluotion of clean milk 

 may be most readily encouraged by obtaining for the milk ]»roducer a reasonable 

 margin of profit. It is shown that the average price paid for milk has not kept 

 pace with the inci'easing cost of feeding stuffs. The grading of milk and the 

 paying of jirices according to grade would be an inducement along this line. 



Ability of colon bacilli to survive pasteurization, S. II. Aykks and W. T. 

 Johnson. Jr. {U. ,s'. Dcpt. Afn:. Jour. At/r. Research, 3 (ID 15). No. .5, /)/). J/Ol- 

 410, fig. 1). — The authors summarize the results of their studies, which are a 

 continuation of work previously notetl (E. S. K.. 20. p. 78). as follows: 



"The thermal death point of 174 cultures of colon bacilli isolated from cow 

 feces, milk and cream, human feces, flies, and cheese showed considerable varia- 

 tion when the cultures were heate<l in milk for 30 minutes under conditions 

 similar to pasteurization. At 60° C. (140° F.), the lowest pasteurizing tem- 

 perature. 05 cultures, or 54.59 per cent, survived; at 62.8°, the usual tempera- 

 ture for pasteurizing. 12, or 6. SO per cent, survived. One culture was not 

 destroyed at 65.6° on the first heating, but in repeated experiments it was 

 always destroyed. There is a marked difference in the effect of heating at 60° 

 and at 62.8°. Although there is only a difference of 2.8°. 87.3 per cent of the 

 cultures which survived at 60° were destroyed at 62.8°. 



" Considerable variation wns found in the thermal death point of the colon 

 bacilli which survivecl 62.8°. When the 12 cultures which survived were heate<l 

 again at the same temiierature. it was found that many did not survive and in 

 each repealed heating different results were obtained. It seems evident that 

 62.8° maintained for 30 minutes is a critical temperature for colon bacilli. 

 Among the 174 cultures studied all were found to have a low majority thermal 

 death point, but were able to survive pasteurizing temperatures on account of 

 the survival of a few cells. 



" The colon test as an index of the efficiency of the process of pasteurization 

 is complicated by the ability of certain strains to survive a temperature of 62.8° 

 for 30 minutes and to develop rapidly when the pasteurized milk is held under 

 temperature conditions which might be met during storage and delivery. Tlie 

 presence of a large number of colon bacilli immediately after the heating process 

 may indicate improper treatment of the milk. If milk is pasteurized at a tem- 

 ])erature of 65.6° or above for 30 minutes, we should not expect, from our 

 results, that any colon bacilli would survive. Consequently under such condi- 

 tions the colon test for the efliciency of pasteurization may be of value. It 

 must be remembered, however, that a study of more cultures may reveal strains 

 of colon bacilli that are able to survive this and even higher temperatures." 



A bibliography of cited literature is api)ended. 



A bacteriological study of blue milk, B. W. Hammer {Iowa Stn. Research 

 Bui. 15 (J9J4), pp. 467-.'t8J. figs. 7). — This is an account of a bacteriological 

 study made of a sample of blue milk coming from a small Iowa farm, but which 

 is thought to have become infected in the home of a customer. 



Careful study of the organism involved proved it to be Bacillus cyanogenes. 

 The organism isolated was examinetl morphologically, culturally, and biochemi- 

 cally. In its action on milk the organism was found to " produce a color in 

 raw milk, in pasteurized milk, and in .sterilize<l milk, although the color pro- 

 duced was markedly influenced by the previous treatment of the milk. 



" Raw milk invariably developed a color sooner than j)asteurized or sterilized 

 milk and the color was also a brighter blue as a rule, being in some cases a sky 



