150 



WINSLOW, ROTHBERG AND PARSONS 



of ordinary nutrient gelatin in tubes of f inch diameter. These 

 gelatin tubes were incubated at 20°C. for thirty days and the 

 depth of the gelatin liquefied was recorded at frequent intervals 

 by measuring down to the surface of the solid portion from a 

 line drawn with a glass pencil around the tube at the original 

 level of the medium. 



Of the total of 180 strains studied, 101 liquefied gelatin to 

 some degree within thirty days. Of 100 white strains, 47 (47 

 per cent) were liquefiers; of 80 orange strains 54 or 67 per cent 

 were liquefiers, indicating a slightly higher tendency to attack 

 gelatin within this color group as noted in the Systematic 

 Relationships of the Coccaceae. It was also suggested by the 



Winslows that the orange forms when they do liquefy act more 

 rapidly and more vigorously than the white cocci. We find that 

 there is indeed a slight difference of this kind as indicated by 

 table 1, which, however, shows the differences observed by us 

 to be much slighter than those recorded in earlier investigations. 

 The Winslows report an average liquefaction after thirty days 

 of 2.2 cm. for the orange forms and 1.1 cm. for the white strains; 

 while Kligler cites figures of 3.5 cm. for the orange and 1.4 cm. 

 for the white forms. The Winslows studied only 16 white 

 liquefying strains and Kligler only 3; and their results are prob- 

 ably not typical. The fact that the absolute values recorded in 

 the present investigation are so much higher than those reported 

 by the Winslows may in part be attributed to the preliminary 

 cultivation in gelatin broth; but it seems clear from the fairly 

 large series of strains studied by us that the difference in rate of 

 gelatin liquefaction between the white and orange staphylococci 

 is only a relative and a rather slight one. 



