54 REPORT OF DEPARTMENT OF BACTERIOLOGY OF THE 
soluble in the presence of chalk, and he and Russell & Wein- 
zirl’® made experimental cheeses to which they added starters of 
various organisms. ‘These and other investigators have attempted 
to work out the flora more in detail but the methods at their dis- 
posal were not equal to the task. 
Gradually it is coming to be recognized that representatives of 
both of these bacterial groups may function in the ripening proc- 
esses. Gorini!* has pointed out that the division between enzym- 
forming and acid-forming bacteria is not clear cut but that there 
are many bacterial forms in cheese which produce appreciable 
quantities of both acid and enzyms. He has striven to show that 
the group having these two characteristics in common is particu- 
larly important. 
This bulletin marks the application of an improved technique to 
this complex question and it is believed that it thereby furnishes 
more exact and detailed information regarding the bacterial life 
of the cheese than has been given by previous workers. 
GHEER SHS sel CGE: 
KIND. 
As we intended to study the flora of cheddar cheese, all of the 
cheeses used were good examples of full cream American cheddar 
and were made in accordance with the approved methods by ex- 
perienced makers. As they ripened they proved to be of very high 
quality, being practically free from any unusual flavors or other 
defects. 
The cheeses VIIJ and X were pressed. in the form of Young 
Americas, each weighing about 10 pounds; while the remainder 
were what is termed “ flats,” ranging in weight from 32 to 40 
pounds. Our object in working with these large cheeses was to 
have a mass sufficiently large to ripen normally in spite of repeated 
sampling. 
ORIGIN. 
In order that these cheeses should represent more than the flora 
of our own dairy we obtained cheese from four commercial fac- 
tories, all of which are characterized by a very fine product. Cheeses 
* Russell, H. L. and Weinzirl, J. The rise and fall of bacteria in cheddar 
cheese. . Cent. Bakt., II Abt, 3: 456-467. 1897. 
*Gorini, C. Ueber die saure labbildenden Bakterien der Milch. Cent. 
Bakt., II Abt., 8: 137-140. 1902. 
