New York AGRICULTURAL EXPERIMENT STATION. 181 
as phosphates becomes water-soluble very early in the ripening, 
so that any insoluble calcium which may be present could not be 
there as phosphates. The calcium as calcium lactate would be 
in the water extract so that the only way the calcium could 
be combined would be with the paracasein. As confirming this 
we have the fact as shown in Table IV that the whole of the 
calcium does not become water soluble until ‘all the paracasein 
has been changed from the salt-soluble form to a form insoluble: 
in both water and salt solution. 
Work is being done by Dr. L. L. VanSlyke and the author to 
determine the nature of these changes in the cheese and what 
the changes in the paracasein are. 
Pore oNCLION OF. THE LACTIC ACID BACTERIA. 
Previous work done by the author while connected with the 
U. S. Department of Agriculture shows that the rennet added 
to curdle the milk and the bacteria present in the cheese play. 
practically no part in the ripening of the cheese after the first 
ten or twelve days; that is, up to the time when proteolysis 
begins. The actual ripening of the cheese from that point is due 
to the action of molds growing upon the surface of the cheese. 
The real function of the bacteria may be placed under two 
headings. 
1. To change the milk sugar into lactic acid thereby producing 
the changes in the paracasein noted in this paper. 
2. By their growth in great numbers and their production of 
acid to inhibit nearly all other forms of bacterial life. 
There seem to be good grounds for believing that the part the 
lactic organisms play in the ripening of nearly all types of cheese 
is the same, 1. e., to develop acid ‘and thus bring about the changes in 
the paracasein. The extent of this change is quite different in 
the several types of cheese and may be one of the fundamentals 
which differentiate the types, their form of ripening and their. 
_ flavor. . | 
As an illustration, take the camembert and cheddar types. 
In the camembert type the paracasein-all becomes soluble in 
salt solution and all this is further changed into an insoluble 
form. In cheddar cheese the paracasein is all changed into the 
salt-soluble form but not enough acid is produced (due to the 
method of making this type of cheese) to change this all into. 
