bays: classifying staphylococci. 83 



It will be observed that results in table I have divided all of 

 the staphylococci into five classes. Class I, those staphylococci 

 which ferment all four of the sugars, dextrose, lactose, saccha- 

 rose and mannite ; class II, those that ferment dextrose, lac- 

 tose, saccharose, but are negative upon mannite ; class III, 

 those fermenting dextrose and saccharose but negative upon 

 lactose and mannite ; class IV, includes all staphylococci which 

 failed to produce acid in any of the four sugars; and class V, 

 includes four strains that are irregular. 



It can readily be seen that there is no correlation between 

 these classes in source, pathogenicity or pigmentation. For 

 this reason, classifying staphylococci purely on fermentation 

 reactions, disregarding pigment production and liquefaction of 

 gelatin, does not seem to give a satisfactory classification. 



The second phase was to assume pigmentation as a primary 

 classification, using white, yellow and orange, and subdividing 

 each of these, making use of the fermentation reaction of the 

 sugars. In doing this, I have assumed that dextrose, lactose 

 and mannite are of importance in the order named and have 

 developed the classifications which are shown in table II. 



Again it can be seen that there is no apparent correlation 

 between these fermentation reactions and pigmentation or 

 source or pathogenicity. 



Subdivision 3 of this problem comprises an application of 

 the phenomena of hemolysis to subdivision of various pig- 

 mented types of staphylococci. There are various and con- 

 flicting statements in literature as to most suitable kind of 

 blood for determining hemolysis by staphylococci. It is quite 

 generally recommended that a washed suspension of red blood 

 cells be used, but for routine laboratory work this process is 

 not ordinarily followed, largely because of the lack of facilities 

 and the desire for speed. In order to duplicate ordinary lab- 

 oratory methods, I have made use of blood agar prepared by 

 adding defibrinated blood to melted agar cooled to 45° C. 



Before attempting this work I tried the hemolytic properties 

 of these organisms for rabbit, sheep and human bloods to de- 

 termine which gave the most positive and fairly consistent re- 

 sults. These are embodied in table III. 



