EXPERIMENT STATION BULLETINS. 415 



Bacterium lact. acidi Micrococcus roseus 



Staphyloc. pyogenes albiis Sarcina flava 



Staphyloc. pyogenes aureus Actinomyces 



Streptococcus pyogenes Saccharomyces rosaceus 



Micrococcus sulfureus Molds. 

 Most samples contained 



Bacterium prodigiosum Micrococcus cerasinus 

 " coli 



The butter in Stuttgart must have been of a very low quality, containing 

 regularly 11 different species. 



Staphylococcus pyogenes aureus and albus are identical with Micrococcus 

 lactis varians and albidus Conn. Whether Micrococcus sidfurens and Sarcina 

 flava are identical with some of our organisms cannot be decided because the 

 description of Migula gives no data about their acid production in different 

 sugars and their development in milk. Streptococcus pyogenes, Bacterium 

 coli and prodigiosum, Micrococcus roseus and cerasinus are never found in 

 our samples. The Actinomyces may be identical with one of our so-called 

 Streptothrix, but since Reitz gives no description at all, it is not certain. 

 The Saccharomyces rosaceus is probably a pink Torula, since red Saccharo- 

 mycetes are never described. Rogers found in old, fishy butter, liquefying 

 bacteria, mostly spore-producing kinds, and ToruZa yeasts, which perhaps 

 belonged to different species; his very short description does not disagree 

 with the description of our small, irregular yeast. 



We intended also to identify our bacteria with those isolated by Pen- 

 nington from cold stored milk; this was, however, impossible, because in 

 the publications there is nothing given but the name, and the description in 

 Chester is so incomplete that we could not compare the different bacteria. 

 Pennington found only two species more frequently, namely Bacillus for- 

 mosus 12 times and Bacillus solitarius 9 times. Besides this, there was 

 Bacillus cloacae 4 times, Bac. Raveneli 3 times, 4 bacteria were found twice 

 and 19 organisms only once. Therefore, we cannot speak of a character- 

 istic flora in cold stored milk. 



THE ORIGIN OF THE BACTERIA IN BUTTER. 



The origin of the bacteria in butter is not always the same. Several 

 kinds are the regular inhabitants of milk, as the lactic acid germs and the 

 Micrococcus lactis varians, which was found most regularly in our butter 

 samples. This germ is supposed to be one of the bacteria ordinarily found 

 in the cow's udder (see p. 37). Oidium lactis is almost always present in 

 milk. These organisms may be prevented by pasteurization of the cream 

 before the ripening with a pure culture. 



Other bacteria are derived from the wash water. B. fluorescens lique- 

 faciens probably comes from this source. The Iowa Exp. Sta. (Bui. 71) and 

 the Kansas Exp. Sta. (Bui. 138, p. 212) found a direct relation between the 

 bacterial content of wash water and the keeping quality of butter. Lloyd 

 (Journ. British Dairy Farmers' Assoc, 18, (1904), p. 136) uses twice pas- 

 teurized skimmed milk for washing. 



