l82 



C.-E. A. WiNSLow AND Anne F. Rogers 



erty which on the average shows a definite correlation with other 

 properties has systematic significance. 



Of the cocci studied, 145 showed in two tests a Gram negative 

 reaction on both occasions, and 209 two positive reactions, while 

 146 were once stained and once decolorized. Grouped thus in 

 three divisions, we have seen that the positive reaction is charac- 

 teristic of the parasitic forms, while saprophytic forms and packets 

 tend to be Gram negative. With surface growth only an insignifi- 

 cant relation appears, the less richly growing forms showing a slightly 

 higher proportion of positive reactions. 



TABLE 18. 

 Correlation between Gram Stain and the Fermentation of Dextrose Broth. 



Acidity Produced 

 (Per Cent Normal) 



o . o and over 



o. i-o. 2 



0.3-0.6 



o. 7-2.0 



2 . 1 and over 



TABLE 19. 

 Correlation between Gram Stain and the Fermentation of Lactose Broth. 



The relation between the Gram reaction and the fermentation 

 of carbohydrates is a surprisingly close one. Each line in Tables 

 18 and 19 showing the distribution of organisms among the grades 

 of acidity forms a regular curve. In each case the mode of the 

 Gram-negative cultures occurs at the neutral point, and that of the 

 Gram- positive cultures at a moderately high acidity, with the doubt- 

 ful cultures showing an intermediate relation. 



TABLE 20. 

 Correlation between Gram Stain and Optimum Temperature for Growth. 



