114 REPORT OF DEPARTMENT OF BACTERIOLOGY OF THE 
Very few specimens of yeasts have been found although an effort 
was made to prepare plates especially suitable to their habits of 
growth. 
Detailed description A weakness of previous studies of this 
subject, with the possible exception of that of Conn, has been the 
fact that the organisms were not described in such a manner that 
succeeding workers could recognize them. Accordingly each new 
student was compelled to study the flora anew and with little as- 
sistance from the previous work. Under such circumstances pro- 
gress was necessarily slow. 
With the recent improvement in the manner of recording the 
reactions of the cultures and of arranging this record for compari- 
son it is believed that this difficulty has been largely overcome. 
Future students should be able to build upon the present founda- 
tion and a fairly complete knowledge of the cheese flora be made 
comparatively easy. 
The group number expresses the spore formation, relation to 
oxygen, liquefaction, fermentation of dextrose, lactose and saccha- 
rose, nitrate reduction and color. ‘There are many other relations 
to their environment with regard to which cultures will differ. The 
individual cultures have been tested with regard to a considerable 
number of these and the results are given in Table XX VII. 
In this table the cultures are arranged in the numerical order of 
their group numbers. The type name according to Conn is given 
in all but a single case; Bact. 212.33307 did not seem to be included 
in the forms studied by him. 
In addition to the facts expressed in the group number the 
observations upon the cultures in connection with 26 other items is 
recorded by -++- or —. The numerals at the left of these signs give 
the number of pure cultures found which were alike in these partic- 
ulars. 
Of the 148 cultures which were thus studied the 33 groups are 
subdivided into 93 variations or an average of less than two cul- 
tures to a variation. This illustrates on one hand the variation 
which is constantly met in bacteria from cheese and on the other 
the hopelessness of attempting to classify cultures into divisions 
which should include only members which are identical. Were the 
list of reactions sufficiently extended it is doubtful if two cultures 
could be found which would have an identical record. 
