24 STORRS AGRICULTURAL EXPERIMENT STATION. 
in growth upon various media, but also from their action on 
milk. T‘hey certainly represent a type of dairy organisms _ 
comimon everywhere. Many of the lactic organisms hitherto 
described by different bacteriologists clearly belong to this’ 
type, although slight differences in described characteristics 
perhaps indicate different varieties. This is true of the Bacte- 
rium acidi lactic? of Giinther and Thierfelder, Bacterzum lactis 
actdt of Leichmann, Bacillus XTX. of Adametz, Bacillus a. of v. 
Freudenreich, J/. actdi laevolactdi and B. acidi laevolactici of 
Leichmann and several of the types described by Storch. The 
pure culture used in cream ripening and put on the market by 
Hansen is a culture of one of this type of lactic organisms, and 
the same is true of the pure cultures of Witte and Barnekow. 
All of these organisms agree very closely in general characters 
and are doubtless closely related. In this region this type, 
represented by No. 206 and No. 202, is the most abundant 
milk bacterium, at least in milk obtained in the ordinary man- 
ner and allowed to stand for several hours before testing. 
The next most important dairy species in this vicinity is 
No. 208, which I have regarded as identical with LB. lactis aero- 
genes. This is found almost universally, although never in 
very great numbers. The organisms included under this 
number, however, have shown very wide variations, and it is. 
quite possible that a number of distinct types are here included. 
At all events, it 1s quite certain that if all these forms are to be 
regarded as one species, several quite distinct varieties must 
be recognized among them. The distinctive characteristics of 
these species are, (1) the intense acid that the colonies produce 
in litmus gelatin; (2) the abundance of gas which is developed 
when they grow in milk sugar bouillon or in milk; (3) the 
uncertainty as to their power of curdling milk, this occurring 
commonly at high temperatures though not,commonly at room 
temperatures; and (4) the distinctive odor of sour milk which 
is found in milk that has been curdled by means of them. 
BL. acidt lactict, 1. and II.,.Nos. 206 and 202, although they 
curdle milk with the production of lactic acid, do not give rise 
to the typical sour milk odor, and neither of them develop any | 
trace of gas in the milk. Iam therefore convinced that the 
ordinary souring of milk is produced in part by the action of 
this No. 208, and that typical sour milk, with its tendency to 

