CLASSIFICATION OF DAIRY BACTERIA. 105 
and negative signs. This plan, advanced some years ago by 
Fuller, has proved useful, and inasmuch as it has been pro- 
visionally adopted by the American Society, we have made use 
of it in the tables of our key. In our own opinion the plan 
advanced by Gage and Phelps in using numbers that have cer- 
tain arbitrary meanings is far more satisfactory and far more 
usable than this plan which the American Society has adopted; 
but it is better to have uniformity in the matter even at the 
expense of some loss, and we have therefore adopted the plan 
of the American Society. All of our species are arranged in 
tables in this way, the tables being so grouped that organisms 
which are most closely related to each other come in proximity. 
With this plan it is only necessary in order to identify the rela- 
tions of a new type of bacterium, to fill out on one of the cards 
‘prepared by the American Society, the blanks left for the in- 
sertion of the characters, and then to place this blank upon the 
table in the following pages and running it up and down the 
page until there is found one organism with which the plus 
and minus signs practically agree. When this is found it is 
sure that the allies of the species under consideration have been 
identified, though it may not agree in all details. In this table 
we have also used the group numbers as directed by the Ameri- 
can Society of Bacteriologists, this group number being another 
important aid in identifying a culture and placing it among its 
allies. 
In a number of cases we have found that what.we believed 
to be the same organism comes under two different heads in 
our classification; for instance, a culture has been described as 
a Bacterium and another one as a Coccus, and yet when care- 
fully studied out in all other respects they are found to be the 
same. Under these circumstances we have been uncertain as 
to where it should be classified and we have therefore placed it 
under both divisions of Coccacece and Bacteriaciae. The same 
thing has occurred occasionally with organisms that liquefy or 
do not liquefy gelatine. In all such cases cross references are 
inserted to indicate these probable relationships. 
It should be finally stated that the forms which we recognize 
in the following pages which we name must be regarded as 
groups and not species. This is not at all material, inasmuch 
as we have no conception whether the term species has any 
x 
