1 62 Bulletin of Laboratories of Denison University voi. xi.j 
are present in it only because they were present in the milk, 
perhaps by accident or carelessness in handling the product, but 
never really flourish in the cheese medium. 
The well-nigh universal distribution of the gas germs is 
striking and important. That these bacteria are a serious detri- 
ment, the cheese-maker and numerous experiments bear con- 
vincing testimony. Although the above data were not ob- 
tained with any special reference to this subject, yet in most 
cases we find bad flavors associated with a high content of gas 
organisms. Their universal presence is explained, perhaps, in 
that most of these species are also acid producers, hence they 
find a favorable medium in the cheese. From an economical 
aspect, to overcome these germs is a very important problem 
on which considerable labor has been spent.' The use of pure 
cultures of lactic organisms, in one form or another, has been 
recommended and if practiced in accordance with bacteriolog- 
ical methods, would undoubtedly be of considerable help ; but 
preventative measures should also be adopted. Pure cultures 
cannot overcome the effects of slovenliness in any of the de- 
partments of the dairy. Fortunately, the Wisconsin curd test 
furnishes an important aid in determining- any abnormal and ex- 
treme abundance of these germs and thus the blame for much 
of our inferior product may be located. 
To recur to the lactic acid type of organisms, there can 
scarcely be any question that they are directly beneficial, al- 
though playing no important role in changing the casein into 
soluble products. Their general distribution and preponder- 
ance in the cheese both indicate their usefulness. Further, as 
we have already stated, the cheese-maker’s art is an empirical 
attempt to produce these very germs, at least such is the case 
with Cheddar cheese. It would be interesting to know whether 
they are also present in other kinds of cheese. Some analysis 
that we have made would seem to indicate that they are essen- 
tial to many other varieties, but our data are not sufficient to 
warrant such conclusions. A more detailed study of the cheese 
flora is in progress the results of which may be expected in 
due time. 
