98 RELATIONSHIPS OF THE COCCACE^ 



Certain characters are included in the table which have 

 been omitted from Figure I and vice versa; but the two 

 together furnish a clear picture of the different groups. 

 The contrast between the Paracoccaceae and the Meta- 

 coccaceae in regard to habitat, gram stain, surface 

 growth, and acid production is brought out in Figure I. 

 The table shows in addition the difference in average 

 acid production. The peculiar relations of temperature 

 to chromogenesis in Aurococcus and Rhodococcus are 

 shown in the figure, as well as the high liquefying power 

 of Aurococcus. The slight action of Rhodococcus upon 

 gelatin, and the high reducing power of this genus, are 

 indicated in the table. 



The generic name Aurococcus was suggested by us for 

 the cocci characterized by the production of an orange- 

 yellow pigment, corresponding to the eighth and ninth 

 chromas under the Cadmium Orange column of the frontis- 

 piece. These forms have previously been grouped with the 

 yellow chromogens in the genus Micrococcus. Their dis- 

 tribution is, however, about a center quite distinct from 

 that of the yellow micrococci, as indicated in the 

 frontispiece; and in all their characters the orange and 

 yellow forms are strikingly different. 



Of our 500 cultures 180 fall naturally in the genus 

 Aurococcus. Of these, 135, or 76 per cent, were isolated 

 from the human body. Eight strains only, or 4 per cent, 

 showed packets. On the other hand, 124, or 69 per cent, 

 showed a uniformly positive reaction to the Gram stain, 



