20 STORRS AGRICULTURAL EXPERIMENT STATION. 
uncertain whether I was dealing with wholly new species or 
not. Some of the species described are very abundant and are 
found very frequently in dairy products, while others are rare, 
being found only once or twice. In my original laboratory 
notes each of these species has been entered by number. But 
it has seemed to me wisest in the following pages to apply 
names to such species as are clearly distinct and new. I have 
looked through the literature of systematic bacteria as carefully 
as possible, and wherever I could do so I have identified the 
species I have found with those described elsewhere. This, 
however, has not been possible in a majority of cases. It must 
be regarded as doubtful whether the identification of species 
found in milk with those found in water, soil, and air is accu- 
rate, and when the attempt is made to identify American 
species with those of Europe the uncertainty becomes very 
great. A few well marked species may be thus readily recog- 
nized, but for most species we must, in the present condition 
of bacteriology, recognize that any identifications of American 
dairy bacteria with bacteria from other sources and localities is 
very uncertain. For the most part the dairy bacteria must at 
present be considered by themselves. Where I have been able 
to class my species with those elsewhere described, the classifi- 
cation has been indicated by applying to the organism here 
described the name of the species with which it has been 
identified. 
In regard to the rest of the species which cannot be identified 
with any described species, I have adopted the following plan. 
Wherever the species in question is an extremely common one 
or one that is very easily described and recognized from descrip- 
tion, I have given it a specific name. In using these names I 
have in most cases added the word. /actzs for the purpose of 
indicating the fact that the organism in question is of a species 
foundin milk. In the following pages, therefore, where a new 
name has been applied to a described organism this indicates 
either that it is a very abundant dairy organism or that it is 
one whose characters are so distinct as to indicate clearly that 
it differs from any other described species, and moreover so 
distinct that it can easily be recognized from the description. 
Where the organism in question, however, is found only rarely 
in dairy products and has characteristics so obscure as to make 

