214 RELATIONSHIPS OF THE COCCACE/E 



teen strains showed a reaction between —.001 normal and 

 — .005 normal; sixty-nine a reaction between neutral and 

 .004 normal; twenty- two a reaction between .005 and .009 

 normal; only four were higher. In lactose broth, forty strains 

 gave an alkalin reaction (between —.001 and —.005 nor- 

 mal); sixty-seven were faintly acid, between neutral and 

 .004 normal; only seven were distinctly acid. Growth and 

 color production were in most cases equally good at 20 

 degrees and 37 degrees. The pigment production was 

 generally distinctly yellow, falling under the Light Cadmium 

 Yellow, and Medium Cadmium Yellow, in ninety-three 

 cases (see Frontispiece). 



The homogeneity of this genus, and the lack of data 

 in regard to fermentative power and immunity reactions, 

 make the distinction of specific types somewhat difficult. 

 Among the Metacoccaceae we lack the mass of valuable 

 information which has been accumulated by medical and 

 sanitary bacteriologists with regard to the parasitic forms. 

 Such comparative studies as have been made among the 

 diplococci and the streptococci would no doubt reveal 

 the existence of distinct type centers now unknown. It 

 is possible that characters of great systematic importance, 

 here, may be found in properties which have not, as yet, 

 been studied at all; — just as fermentation reactions proved 

 the key to the streptococci. 



Meanwhile, a few differential characters are at our 

 disposal, — notably gelatin liquefaction and nitrate re- 

 duction. A comparison of these properties in our own 



