104 STORRS AGRICULTURAL EXPERIMENT STATION. 
Bacteriologists, we have endeavored to insert only the salient 
characters. It has appeared to us that the numerous details 
only confuse one in an attempt to identify and classify bacteria. 
When it is so evident that these physiological characters, which 
are largely the basis pf these long descriptions, are capable of 
such great modification by culture, when it is evident that the 
cultures of bacteria which one obtains are likely to come from 
a great variety of sources and therefore to have been subject to 
a large variety of different conditions, it is evident that we may 
expect an almost endless variation in the physiological charac- 
ters of the different cultures. If we donot identify two cultures 
of bacteria as the same until we find that they agree exactly 
in all of the long series of characters given in the society 
blanks, we shall practically never identify any two types of bac- 
teria as thesame. It has seemed to us that this is an absurdity 
and that the recognition of the relations of bacteria will be 
advanced by omitting insignificant details, concentrating our 
attention upon the more important characters. For this reason 
we have in these descriptions omitted much of detail and have 
only given such points of description as have seemed to be 
most salient. 
Following the detailed descriptions we have given analytical 
keys and tables covering all the types. We recognize the 
fact that the bacteria of milk may be grouped in three gen- 
eral groups, the Coccaceae, the Bacteriaciae, and Bacilliariciae. 
These groups are morphological ones, and while, as has already 
been pointed out, we are convinced that to a certain extent 
they run into each other and cannot be sharply distinguished, 
they do represent fairly well marked groups. Under each 
of these heads we have given an analytical key, in which 
the important characters are used for purposes of diagnosis. 
By means of this key it is possible to trace readily to its 
group or to its allies any type of bacterium of which we 
have a tolerably complete description. These analytical keys 
are given for each of the great groups of bacteria. Follow- 
ing these analytical keys we have given finally a tabulated 
key of all of the important characters of the different species. 
In the preparation of this key we have made use of the plan 
adopted by the American Society of Bacteriologists, selecting 
the important characters which can be indicated by positive 
