276 EXPERIMENT STATION KECORD. 



" It is very doubtful whether these products combine with the iuorganic or 

 casein constituents of millv, as is the case of lactic acid, so as to permit the 

 lactic micro-organisms to grow more freely. 



" The period at the beginning of lactic fermentation during which no lactic 

 acid formation can be determined, and during which the number of bacteria is 

 continually increasing, may be greatly shortened by vigorous associate bacteria 

 inlluencing the lactic micro-organisms. 



" Usually the associate micro-organisms disappear with the formation of 

 appreciable amounts of lactic acid ; yet the associate micro-organisms may con- 

 tinue or persist, causing an abnormal lactic fermentation. 



"Associate micro-organisms may influence lactic fermentation by producing 

 • off flavors,' ' oft" aromas,' and an unusual high degree of acidity. Even the 

 character of the acid may be completely changed. 



" It follows that the elimination of ' fifth ' bacteria is the only means of elimi- 

 nating the product causing lactic acceleration, inasmuch as the products may be 

 so stable as not to be destroyed by ordinary means of milk treatment." 



Bacterial associations in the souring- of milk, C. E. Marshall and Belle 

 Farrand {Ceiithl. Bo.kt. [etc.], 2. Aht., 21 (1908), No. 1-3, pp. 7-59).— See 

 abstract above. 



Variation in the chemical composition of butter, C. Crowther {Univ. Leeds 

 and Yorkshire Council, Agr. Ed. [Pamphlet} 66, 1907, pp. 3-23). — Data are 

 reported regarding the percentage composition and the Keichert-Wollny number 

 of 126 samples of butter prepared from cream produced on one farm during 

 two years, and these are discussed in considerable detail with reference to the 

 results of studies made on the causes of variation in the water content of the 

 butter and in the proportion of volatile acids. The water content of butter, 

 according to the author, is very largely determined by the nature and amount 

 of working to which the butter is sul)jected, though a considerable number of 

 other factors also affect it, as the degree of softness of the butter fat, the 

 average size of the butter gi-ains, the temperature of churning and of the water 

 used for washing, the intervals between two workings, thie use of dry or moist 

 salt in working, and others. The chief factors aflecting the proportion of 

 volatile acids present are the stage of lactation of the cows, the climatic and 

 other conditions affecting their comfort, and the character of their food. 



On the relation between clean skimming' and clean churning, J. Jonas 

 (Maclkeritid., 21 (190S), No. 11, pp. 195-202). — In experiments conducted at 

 Ladelund Dairy School (Denmark) cream containing principally small fat 

 globules gave a buttermilk richer in fat than cream with mostly large globules, 

 and though with very clean skimming (0.05 to 0.07 per cent by the Gottlieb 

 method) the buttermilk was richer in fat than when more fat was left in the 

 skim milk, the yield of butter was increased to a much larger extent. It is 

 therefoi'e important that the milk be skimmed as clean as possible. 



Babcock test for butter fat, J. II. Frandson (Idaho Sta. Bui. 63, pp. 6, Jifl^. 

 .}). — General information regarding the method of operating the Babcock test, 

 prepared in response to inquiries from teachers and farmers. 



Besearches into some of the chemical changes involved in hard cheese 

 production, T. A. Coward {Univ. Leeds and Yorkshire Council, Agr. Ed. [Pam- 

 phlet] 68, 1907, pp. 3-23). — From the results of investigations considered in 

 more or less detail the author concludes that " hard cheese manufacture depends 

 in part, at least, on rennet-enzyms-acid proteolysis, 'whereby physical and 

 chemical changes are brought about in the curd. In practice, however, it will 

 evidently be necessary to gage all the agents concerned in both these series 

 of changes rather than any selected one, for, from the foregoing experiments 



