86 STORRS AGRICULTURAL EXPERIMENT STATION. 
It is practically impossible to produce a normal cheese in such 
a way as to avoid contamination with bacteria or molds. It is 
difficult, therefore, to study the relations of organisms to the 
steps of cheese ripening directly upon cheese. Even were this 
possible the complexity of the changes encountered would make 
the interpretation of the phenomena difficult. The activities of 
these molds have, therefore, been studied in pure culture upon — 
a series of media which would give information as to steps of the 
process. While these cultural studies were being made many 
cheeses were made and inoculated with the Camembert and 
Roquefort Penicillia. The measure of success obtained from 
cheese inoculated with the Camembert Penicillium gave good 
practical ground for its continued study. These detail studies 
may be best discussed separately. 
LIQUEFACTION OF GELATINE. 
The liquefaction of gelatine media has been much used as an 
index of digestive activity. All species obtained have been 
grown upon neutral and acid sugar-gelatine and the effects 
noted carefully. 
The difference in action between the molds important in this 
investigation are striking. The Mucor produces a slow but 
rather complete liquefaction; Oidium lactis will gradually soften 
the gelatine so that the center of the colony is liquefied; a pig- 
ment producing Penicillium (recorded simply as ‘‘O’’) will 
liquefy all the gelatine in contact with it so quickly that it comes 
to be a floating colony in a watery pool twice its own diameter 
in a week. Several other species of Penicillium have the same 
effect. The Roquefort Penicillium softens gelatine somewhat, 
but never produces a watery liquefaction. The Camembert 
Penicillium often produces a slight liquefaction under the center 
of the colony, but never extends that liquid area to half the 
total size of the colony. This seems to indicate that the 
Penicillium ‘‘O’’ and its allies would produce a rapid digestion, 
that the Mucor would be somewhat slower, that the Camem- 
bert mold might have some digestive effect, and the Roquefort 
mold very little, if any, value. The test of the ability to 
liquefy the gelatine used gives therefore only indefinite or nega- 
tive results as to any advantageous relation of these particular 
species to cheese ripening. 

