FUNGI IN CHEESE RIPENING. 89 
that either species is able to change the chemical composition 
until the derivatives of casein are almost completely water 
soluble. Such cultures were plated to show their freedom 
from contamination by bacteria before analysis. ‘The resulting 
products give the standard reactions for digestion. These ex- 
periments show that either of these molds is capable of produc- 
ing digestive changes comparable in their completeness, rapid- 
ity and general nature to those shown by analysis to have 
occurred in the ripening of Camembert cheeses. 
DOES THE MYCELIUM PENETRATE THE CHEESE? 
It must be noted carefully that this action of the Camembert 
mold goes on without the complete penetration of the sub- 
stratum by the mycelium of the mold. That this is true is 
readily seen in milk cultures where the limits of the develop- 
ment of the mycelium are sharp and clear. The same fact has 
been demonstrated for cheese by hundreds of sections and care- 
ful cultural studies many timesrepeated. The mycelium forms 
a dense mat upon the surface of the fluid or the mass of curd, 
or the newly made cheese. It follows the irregularities of the 
surface and is not found to enter well-packed curd to any 
extent. It is very difficult to prove that hyphae of this mold 
actually appear in curd of uniform texture below one or two 
millimeters. When found deeper in, careful search usually 
shows a cracking of the surface so that the mycelium may fol- 
low the opening already made. In no case of many hun- 
dreds of cheeses studied and experiments performed has the 
mold been found to fruit in cavities not opening broadly 
upon the surface. This is in marked contrast to the habit 
of the Penicillium instrumental in the ripening of Roquefort 
cheese, which penetrates the channels of the substratum 
and fruits in every cavity large enough to accommodate a co- 
_nidiophore. The Roquefort mold will make every cavity in a 
cracker or piece of bread green with spores, while the Camem- 
bert mold will fruit upon the surface of the bread or cracker 
with only vegetative mycelium inside the bread. 
Definite experiments to prove that this digestive power on 
the part of the Penicillium is due to the secretion of one or 
more enzymes, have given characteristic reactions for digestion 
many times. Without discussing these chemical reactions 
7 
