EXPERIMENT STATION BULLETINS. 401 



descriptions one is never certain that two bacteria are alike, or, on the other 

 hand, one may have a choice between two, three or perhaps four really 

 identical germs which have been given different names. The classification 

 of Conn, Esten and Stocking may have its mistakes — and probably there 

 are some mistakes in the grouping of the different varieties — but it is a book 

 that can easily be used by every bacteriologist. It is possible that the names 

 which we gave to our bacteria are not always the right names; and we may 

 have grouped together different bacteria under the same name, but the error 

 will not be "very large, since their most prominent characteristics, morpho- 

 logical as well as physiological, are alike. 



The species that we have found most frequently in our butter is the Micro- 

 coccus lactis varians, a somewhat indefinite group of Cocci with varying 

 qualities; they are slowly liquefying yellow cocci, producing acid in dex- 

 trose, lactose and sometimes in saccharose. The acid production varies as 

 well as the liquefaction, and often, though not always, the very slowly 

 liquefying varieties give a more pronounced acidity than the more rapid 

 liquefiers. Staph, pyog. aureus belongs to this species. There is no dis- 

 tinct line between these and the non-liquefying Micrococcus lactis aureus, 

 because some liquefy in 5 days, some in 10, some begin after 30 days, and 

 some which liquefied very slowly the first time, when transferred again, 

 began to liquefy after a few days. The color varies in the same way. We 

 often found in fresh butter an orange variety, slowly liquefying and produc- 

 ing acid in all three sugars, and called this Micrococcus lactis varians 0. 

 (orange). The M. I. varians is often found in the udder of the cow, and 

 therefore we understand its frequency in butter. ^ The M. I. aureus is per- 

 fectly described by calling it the non-liciuefying' variety of M. I. varians. 

 The M. I. alhidus is characterized in the same way as a white variety of M. I. 

 varians. Conn, Esten and Stocking suppose that these three organisms 

 all belong to the same species. This agrees with the observation that very 

 often the one type disappears as soon as the other appears, e.g., IV, XX, XXI. 

 The other Cocci are all found in very small numbers and so seldom that it 

 is not worth while giving their description. They may be looked up in 

 the original. Those which are not named are briefly described on page 38. 



The genus Bacterium is not at all so frequent but there are more 

 different species and many of them could not be named at all. These are 

 described on page 38. The most frequent is Bacterium lactis Conni, a non- 

 liquefying, non-acid rod which makes milk alkaline without any digestion. 

 Conn, Stocking and Esten say that they found this bacterium frequently 

 in New York milk, and in the Camembert cheese. 



Bacterium lactis lobatum is a slowly liquefying orange bacterium, pro- 

 ducing acid in dextrose, lactose and saccharose and digesting the milk with 

 acid reaction to a pasty liquid. Bacterium lactis album is a slow liquefier, 

 not acid, curdling and digesting milk with slightly alkaline reaction. Bac- 

 terium lactis Gorinii is a liquefying bacterium, producing acid in dextrose 

 and saccharose, but not in lactose. Milk is made alkaline and completely 

 digested. 



The motile bacteria occur in still smaller numbers. Only Bacillus lactis 

 cochleatus and Bacillus lactis Pruchii are found several times. The first 

 liquefies slowly, makes dextrose and saccharose, but not lactose, acid. Milk 

 is usually curdled and peptonized with alkaline reaction. Bacillus lactis 

 Pruchii produces acid in dextrose only, liquefies rapidly, curdles and digests 

 milk to a yellowish paste. 

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