454 R. S. BREED, H. J. CONN AND J. C. BAKER 



theory that the spherical bacteria do not constitute a distinct 

 evolutionary group but that the parasitic cocci are of an inde- 

 pendent origiD, more modern than the saprophytic ones. 



The position of the genus Streptococcus is a puzzling matter. 

 Jensen holds that rods gave rise to streptococci and that micro- 

 cocci were derived from streptococci. This argument can be 

 used only on the assumption just mentioned that the saprophytic 

 cocci had an earlier independent origin from some other source. 

 There are good reasons, moreover, for thinking that streptococci 

 are more closely related to the chain-forming short rods occurring 

 in milk than to the micrococci; while some bacteriologists place 

 them near the diphtheroids (Mellon, 1917). Kligler (1917) 

 separates them widely from the micrococci. The streptococci, 

 in short, might easily be removed entirely from the Coccaceae; 

 but because of the uncertainty of the whole matter, it seems best 

 to be conservative and leave them, as the committee recommends 

 in the same family with the other spherical bacteria. 



Family 6. Bacferiaceae. There is some question just what 

 this family should include. The committeee makes it include 

 practically all peritrichic and non-motile, non-spore-forming 

 rods, exclusive of the Bulgaricus group. The chief objection 

 to this arrangement is that it tends to place in this family any 

 member of the Pseudomonadaceae that has lost its power of 

 motility. A non-motile, non-spore-forming rod cannot safely 

 be assigned to either of these families until it has been studied 

 sufficiently to make plain its relationships to other bacteria. 

 A possible treatment of the non-motile, non-spore-forming rod- 

 shaped bacteria would be to recognize an appendix to the families 

 of Eubacteriales in which they may be placed until their relation 

 to other better defined species is learned. The mycologists recog- 

 nize a group which they call Fungi Imperfecta Bacteriologists 

 might equally well create a group of Bacteria Imperfecta. 



The committee has placed four genera in the Bacteriaceae. 

 The chief criticism against the selection of these genera is that too 

 great weight has been placed upon pathogenicity. Two of 

 them. Hemophilus and Pasteurella, include animal pathogens 

 only; one, Erwinia, includes only plant pathogens; while the 



