IDENTITY OF THE LACTIC-ACID STREPTOCOCCUS 165 



and Herder (1906) and by AVinslow and Palmer (1910) to be 

 numerous in the intestinal contents of the horse. In the present 

 case, the two cultures in question not only caused an acid fer- 

 mentation in milk, but produced such a vigorous one as to coagu- 

 late the casein. It seems, therefore, that these organisms were 

 able to ferment lactose under favorable conditions but could 

 .not attack it for some reason when growing in the nutrient 

 broth employed for the tests. A similar idiosyncrasy is noted 

 in a few of the cultures reported by Rogers and Dahlberg (1914). 

 If it is conceded that the organisms of this collection numbered 

 from 1 to 50 are representative of the group of true lactic-acid 

 streptococci some significant points are brought out. It is 

 generally stated in bacteriological texts^ that the lactic organism 

 ferments sucrose, while the statement is also found that mannit 

 is one of the substances attacked, but according to our results the 

 group is typically negative with both of these substances though 

 some strains can ferment them. The typical Strept. laclicus, it 

 would appear, ferments glucose, galactose, levulose, maltose 

 and lactose. Of the cultures which failed to ferment either 

 levulose or galactose none attacked maltose. Among the fifty 

 cultures used there were fourteen which acted upon mannit 

 and a similar number which fermented salicin. Nine of these 

 attacked both compounds, thus showing quite a marked corre- 

 lation between the fermentation of mannit and salicin. In 

 most cases the cultures which fermented sucrose or dextrin also 

 attacked both mannit and salicin. 



TEMPERATURE RELATIONS 



It is generally thought that the true lactic-acid streptococcus 

 grows better at a lower temperature than the optimum for most 

 pathogenic bacteria. Although it has not been demonstrated 

 with any considerable number of cultures, the statement is 

 usually made that the lactic organism has an optimum tempera- 

 ture of from 30°^\ to 35°C. Stowell, Hilliard and Schlesinger 



^ See Weigmann's Mikologie der Milch; .Marshall's Microbiology and Buch- 

 anan's Household Bacteriology. 



