166 WINSLOW, ROTHBERG AND PARSONS 



rarer one and this form, as well as the forms which exhibit miscel- 

 laneous fermentative reactions (see table 8) may best be left 

 for the present without specific names. 



The relations of the five principal types of staphylococci dis- 

 cussed above may be summarized as follows : 



A. Orange Pigment 



a. Lactose fermented, gelatin liquefied 



St. aureus Rosenbach, Type, No. 4 of American 

 Museum collection 



b. Lactose not fermented, gelatin not liquefied 



St. aurantiacus Schroter, Type, No. 348 of American 

 Museum collection 



B. White pigment 



a. Lactose fermented, gelatin liquefied 



St. epidermidis Gordon, Type, No. 25 of American 

 Museum collection. St. ureae Cohn, No. 464 of the 

 American Museum collection is apparently identical 

 with St. epidermidis 



b. Lactose fermented, gelatin not liquefied 



St. candidus Cohn, Type, No. 49 of American Museum 

 collection 



St. tetragenus Gaffky which may be differentiated from 

 St. candidus by characteristic grouping of cells in 

 fours and by viscid growth belongs in the same group, 

 (No. 209 of American Museum collection) 



c. Lactose not fermented. Gelatin not liquefied 



St. candicans Fliigge, Type, No. 526 of American 

 Museum collection 



In a group so variable as the staphylococci, it is clear that the 

 conception of species has only a limited value, although it is con- 

 venient to have names associated with the types of most frequent 

 occurrence. Fundamentally we are inclined to agree with Dud- 

 geon in considering the whole group a reasonably homogeneous 

 one; and it seems clear that the central type of the whole genus 

 is the orange-pigment-forming, vigorously-fermenting, gelatin- 

 liquefying, somewhat actively pathogenic St. aureus. As we de- 

 part from this type there is a progressive weakening of the vari- 

 ous biochemical activities of this more vigorous form. The loss 



