38 RELATIONSHIPS OF THE COCCACE^: 



diplococci, is much more feeble than that of other 

 forms, and their fermentative powers are high. Andrewes 

 (1906) has recently emphasized the essentially parasitic 

 nature of the genus Streptococcus, and has ably outlined 

 its general relations to other groups of the Coccaceae. 

 His view that the streptococci have descended from the 

 saprophytic Metacoccaceae is suggestive; and his theory 

 that certain parasitic bacilli have in turn been derived 

 from the streptococci is not improbable. 



It must be emphasized that both diplococci and strep- 

 tococci are recognized by the correlated occurrence of 

 various characteristics and not by the mere presence 

 of pairs or chains of cells. The morphological criterion 

 alone must not be interpreted literally. Cocci of all 

 genera occur at times in pairs; and typical streptococci 

 fail to show well-marked chains in many media. 



With regard to Ascococcus we concluded in our earlier 

 investigation: "The mere property of zooglea formation 

 should not be considered of generic importance, but the 

 few peculiar species which are capable of growing under 

 purely saprophytic conditions and producing large gelati- 

 nous masses, are so far marked off from other cocci 

 as to warrant, in our judgment, the retention of Cohn's 

 genus." We have not examined these organisms at first 

 hand. Further study of the work of others has convinced 

 us, however, that Ascococcus should probably be referred 

 to the Paracoccaceae rather than to the Metacoccaceae. 

 The reasons for this conclusion will be discussed in 



