Generic Characters in the Coccaceae 



187 



acid-formers fail entirely to form nitrites and ammonia. A correla- 

 tion table for lactose, which we have not thought it necessar)' to quote 

 here, shows a similar relation. The high acid-formers, it may be 

 remembered, belong to the genus Streptococcus^ with its weak power 

 of growth on artificial media. 



Our tables of the correlation between carbohydrate fermentation 

 and optimum temperature fail to show any striking coincidences. 

 There is an appreciable tendency for the higher acid-formers to 

 grow better at 37°, and for the alkaline or neutral forms to grow bet- 

 ter at 20° ; but we have not considered this important enough to war- 

 rant the reproduction of the tables. 



TABLE 28. 

 Correlation between Gelatin Liquefaction and Fermentation of Dextrose Broth. 



TABLE 29. 

 Correlation between Gelatin Liquefaction and Fermentation of Lactose Broth. 



The relation between the organisms which ferment the sugar broths 

 and liquefy gelatin is shown in Tables 28 and 29. These tables 

 may be considered together, as they reveal practically the same law. 

 The relation between acid production and gelatin liquefaction is 

 evidently a somewhat complex one. The forms which fail to ferment 

 carbohydrates for the most part exhibit a moderate amount of lique- 

 faction. Next comes a group of the moderate acid-producers which 

 liquefy most actively. Finally, the highest acid-formers are mostly 

 non-liqueficrs. We shall get more light on these three groups when 

 we come later to consider the classes of the cocci according to their 

 chromogenesis. 



