I1O REPORT OF DEPARTMENT OF BACTERIOLOGY OF THE 
On the same graph is shown the average of the commercial 
scores of 6 of the cheeses. Here again the secondary rise shown 
at 80 days is due to the tardy ripening of Cheese 4.6 V. This graph 
brings out sharply the fact, observed in connection with each indi- 
vidual cheese, that there is a very considerable germ content in 
the cheese at the time when the latter has become commercially ripe. 
For the sake of comparison the quantitative results on six cheeses 
as given by Russell & Weinzirl’® are shown in Graph XI. The tem- 
perature of ripening in these two sets of cheeses was not the same 
and the observed numbers are higher in the second set but the out- 
line of the graph in the two cases is very similar. Accordingly, 
these two graphs may be taken as fairly representing the average 
changes in germ content in normal cheddar cheese; but at the 
same time the fact must not be lost sight of that in the individual 
normal cheese the germ content may depart widely from this 
average. This is shown in Cheese 4.6 IX which showed a maxi- 
mum content at twenty-five days instead of at four days as shown 
by the composite graphs. 
A graph based on results from three Canadian cheddar cheeses 
was published by Harrison.” This curve reached a maximum of 
450 millions per gram at 3 days and then promptly fell to less than 
r million at 57 days. Except for its amplitude this curve closely 
resembled the two which are here given. 
QUALITATIVE SUM MARY. 
Germs found.— When we remember that the milk from which 
the cheese is made receives substantial additions to its flora from the 
soil, the barn and the milking utensils it is natural to expect that the 
cheese will contain an extensive mixture of different forms. Not- 
withstanding the effort which was made to find the representatives 
of all the different forms present, the total number of distinct 
groups found in the nine cheeses which have been studied is sur- 
prisingly small. Over three hundred cultures were isolated from 
these cheeses, these selections being intended to include all differ- 
ences in colony growth. These pure cultures were then studied both 
morphologically and culturally and in the course of this study many 
of the duplicates were discarded. The remaining one hundred sixty- 
seven cultures were studied in great detail and classified according 
7° See note 13. 
2 258 -~ ~ Re . . oe . 
‘Harrison, F. C. The ripening of cheese and the role of microorganisms 
in the process. Trans. of the Canadian Institute, 7: 103-134. Igor. 
