
— BACTERIA IN THE DAIRY. 45 
After Hueppe, Marpmann, Grotenfelt, and Keyser have iso- 
lated milk-souring organisms which agree very well with 
Hueppe’s bacillus. Many other investigators have isolated 
quite a number of organisms which sour milk, but which are 
not like Bacillus acidi lactic. 
- Investigators, both in Europe and the United States, having 
sought to discover Hueppe’s bacillus, and frequently failing to 
do so, though obtaining other milk-souring organisms, have 
concluded that there are a number of different kinds of 
organisms which have the power of producing lactic acid from 
milk sugar and thus precipitating the casein of the milk. 
This, doubtless, is true, but it does not preclude the fact that 
there may be one organism-which is so universally found in 
dairies, and is so commonly the cause of milk souring, as to 
deserve to be regarded as the lactic organism of milk par 
excellence. 
The question whether there is one or many organisms which 
commonly sour milk was discussed pro and con until 1894, 
nothing definite being determined. 
At this time Drs. Gtinther and Thierfelder published the 
results of their work.* The character of their work was of the 
highest order. ‘Their specimens of milk came from a large 
number of milkmen around the City of Berlin, giving a check 
to those specimens which might be abnormal, and ‘which if, by 
chance they were the only ones studied, might give an errone- 
ous conclusion. ‘The method used in the gelatine plate cultures 
was to put into the prepared gelatine a definite amount of cal- 
cium carbonate. This made a somewhat dense medium, but, 
since the carbonate is very soluble in acids, wherever an acid 
colony developed it would become surrounded by a clear spot. 
From a large number of experiments, and the constancy of 
results, they concluded that there was one organism identical 
with Ljister’s Bacterium lactis and Hueppe’s Lacillus acide 
lactict, which caused the true ordinary souring of milk. 
II.—GENERAL STATUS AND OUTLINE OF FACTS. 
In the United States there had been no analytical work on 
the acid organisms of milk as a distinct work by itself, until 
October, 1894, when a series of experiments were commenced 
* “ Bacteriologische und Chemische Untersuchungen iiber die spontane Milchgerin- 
nung.’ Aus dem Hygienischen Institut der Universitat, Berlin. Archiv fiir Hygiene. 
