DAIRY FARMING DAIRYING. 481 



averages of the S lots where a commercial pure culture starter was employed. 

 An between gathered cream and cream separated from whole milk the scores 

 were decidedly contradictory. 



The samples with high acidity came from creameries where the conditions 

 were bad. The fat was decomposed in all samples stored at 5°. At lower tem- 

 peratures different results were obtained, in some cases a distinct increase of 

 free acids, in others only a slight decrease or increase. Acidity and scoi'e were 

 not always related. There was no apparent relation between tlie total amount 

 of free acid and the amount of volatile free acid. 



"The most interesting result of our chemical analyses of l»utter is certainly 

 the fact that samples which are scored rancid or even very rancid did not have 

 the slightest increase of acidity. This seems to indicate that rancidity of cold 

 storage butter is not connected with a hydrolysis of fat in the ordinary way, 

 and for the same reason can not depend upon decomposition products of gly- 

 cerin. It seems improbable that fat should be decomposed in any other way, 

 since we can not conceive of an oxidation in the interior of a 60-lb. butter tub, 

 and an anaerobic decomposition is almo.st impossible because of the lack of 

 oxygen in the fat molecule." 



In identifying the bacteria the classification of Conn, Esten, and Stocking 

 (E. S. R., IS, p. 979) was used. A total of 87 different species of organisms 

 was found, most of them only once or twice. The lactic-acid bacteria were the 

 only organisms regularly present. The most frequent species was Microcncnis 

 hicMs varians. An orange variety of this species was often present in fresh 

 butter. All of the yeasts found were nonspore producers. The most frequent 

 molds were Ouliuni, lactis, PenicUlium gJaucum, and AspcryiUus fflaucns. In no 

 single instance was an organism found which failed to grow well under aerobic 

 conditions. 



The lactic-acid bacteria in percentages of the total number found in fresh 

 butter decreased fairly regularly, there being in November 14 to 17 per cent of 

 the original number alive, and in February only 6 per cent. The decrease of 

 bacteria seemed to be connected with the concentration of brine in the butter, 

 though salt was not the only reason for this decrease. " The better keeping of 

 bacteria in the high salted sami>les can be explained in two different ways. 

 Probably the low salted I)utter was frozen in cold storage and the bacteria 

 could no longer multiply but died slowly, as was found in the iced milk by 

 Risclioff; whereas in tlie high salted butter the brine is not frozen and the 

 bacteria liave a chance for a very slow development. It may be possible, how- 

 ever, that the brine surrounded by fat and distributed in small drops does not 

 solidify in cold storage. The bacteria of the low salted butters develop moi-e 

 rapidly and of course decrease earlier than the slower growing germs of the 

 high salted butter." The decrease of the nonlactic bacteria in November was 

 about the same as that of the lactics. while in February there was no further 

 decrease but apparently a slight increase of the nonlactics. Tlie frequency of 

 each species is given in detail. 



A small irregular yeast was the most interesting organism because of its 

 frequency and its high number, which reached several millions in some samples. 

 It was found comparatively seldom in fresh butter but developed in storage 

 rapidly in spite of the cold and salt. The February examination showed a 

 decrease in number but not in freipiency. A liquefying yea.st was not found 

 in the warm storage but kept its frequency in the colder ones. A round yeast, 

 on the contrary, grew almost exclusively on samples kept above the freezing 

 point. A ])ink yeast disappeared in the coldest storages in February. 



Only 4 fat-splitting organisms were found in fresh butter and none in old 

 butter. Rancidity may have been caused iu some cases by these organisms, but 



