SO-CALLED GERMICIDAL PROPERTY OF MILK. 103 
in these experiments which makes them differ from the experi- 
ments previously discussed. In the first two experiments either 
Bact. lactis acidt or B. lactis aerogenes was shown to exist in 
the fresh milk. In the present experiments, however, the 
acid organisms consisted of miscellaneous species, and none 
of the typical lactic types showed themselves in the plates. 
Several of the acid species found in the fresh milk disappeared 
before the end of the experiment, other species remained about 
the same in numbers, while others which did not appear in the 
first plates formed the predominating acid species at the close. 
The two chief lactic acid types, namely B. Jactis aerogenes and 
Bact. lactis acidi, began to appear in the plates made at the 
end of six hours, and increased continuously until at the end of 
the experiment these two types comprised the greater part of 
the acids present. There were also, however, a few of some 
of the other species present. 
The results of these experiments seem to show that the true 
lactic organisms were present in the fresh milk in such small 
numbers that they did not appear in the first set of plates, but 
were there in sufficient numbers to make themselves known by 
the end of six hours, and became more and more abundant 
from then on. It is evident, therefore, that they increased 
from the outset as in the preceding experiments. The further 
fact is here revealed that certain other acid producing species 
do not find in milk conditions especially favorable for their de- 
velopment. They therefore drop out with greater or less rapid- 
ity during the early part of the ripening period. In milk where 
this condition exists, the decrease in the number of the mis- 
cellaneous acid species may be greater than the increase in the 
number of the true lactic acid species, and the result will be a 
smaller number of acid organisms than was contained in the 
fresh milk. 
DISCUSSION OF GROUP III. 
In this group are included experiments where the results 
were of quite a different nature from those included in the first 
two groups. 
In these experiments there was usually a falling off inthe 
total number of organisms during the first few hours, as in the 
preceding experiments. Sometimes the acid organisms in- 
creased in numbers from the very start, as shown in Table 35, 
