bays: classifying staphylococci. 91 



The fifth subdivision of this paper has to do with the action 

 of all staphylococci upon lead acetate agar. A summary of 

 this data is embodied in table I. It will be observed that, with 

 two exceptions, all staphylococci isolated from pus or boils 

 blackened lead acetate agar. I doubt, however, that this could 

 be depended upon to denote pathogenicity. 



In regard to the sixth subdivision of the paper applying to 

 the various hydrogen ion concentrations, I hope to do more 

 extensive work in the future. I selected 6 from class 1, table 

 I, 6 from class 2, 2 from class 3, and 4 from class 4, and grew 

 them in dextrose dipotassium phosphate broth, as described in 

 the paragraph on technique, and determined the hydrogen ion 

 from day to day for a period of five days. 



These results suggest the possibility of dividing staphylo- 

 cocci into subdivisions depending upon the limiting Pj^. This 

 is analogous to the attempt to subdivide the coliserogenes 

 group. It might be of some value if used with pigment pro- 

 duction as a basis of classification and the high ratio deter- 

 mined for white, yellow and orange separately. 



I have also considered the value of the group number sys- 

 tem as suggested in the descriptive chart of the American As- 

 sociation of Bacteriology, but have decided not to include the 

 various group numbers of the various staphylococci in question. 



summary and conclusions. 



That disregarding pigmentation and liquefaction of gelatin 

 staphylococci may be arranged into five types according to 

 their ability to ferment dextrose, lactose, saccharose and man- 

 nite. These types do not correlate with any other observed 

 characteristics such as source, pathogenicity, pigmentation or 

 liquefaction of gelatin. It would seem that this method of 

 classifying staphylococci would only lead to confusion and 

 offers nothing of basic value. 



That while routine laboratory work might warrant only the 

 data on morphology, gram stain, type of growth and pigment 

 production on plain agar slants, yet it would seem advisable, at 

 least from the standpoint of comparison when reporting upon 

 staphylococci in the literature, to follow some such plan as 

 follows : Gram stain, pigment production, liquefaction of gela- 

 tin, action on blood agar plates where kind of blood, amount 

 and Pjj of medium are given, and the fermentation reaction in 

 dextrose, lactose and mannite. Instead of blood agar plates it 



