NATURAL BACTERIAL SYSTEM 269 



very slightly acid-forming cocci (among which must probably be 

 reckoned the gonococci and the meningococci too, as well as 

 Gram-negative streptococci, if such exist) we might simply use 

 the generic name Coccus, or, if they should turn out to have 

 terminal flagella, Coccomonas. 



Even as unjustifiable as it would be to unite all the spherical 

 bacteria into a great family, Coccaceae, would it be to set up the 

 family Spirillaceae. The rule is indubitably that in every bac- 

 terial family we may meet with both sphere, rod and screw 

 forms. Certainly the lophotrichic spirilla, both in regard to 

 their morphological and to their biological properties, form a 

 natural group. This thoroughly justifies the setting up of a 

 genus, Spirillum, or better Spiromonas, a new designation, 

 which would also make it possible to incorporate nearly related 

 monotrichic species in this group. We should surely be war- 

 ranted in doing so, since in other genera of cephalotrichic rods 

 we meet with both monotrichic and lophotrichic species. The 

 genus Vibrio, which the bacteriologists, one and all, reckon 

 among the family Spirillaceae, can on the contrary scarcely be 

 maintained, since these organisms pass gradually through the 

 phosphorescent bacteria into the cephalotrichic rods. 



The only morphological property of the bacteria which can 

 perhaps be taken into account as a family character, is spore 

 formation. Yet this property as such is not used in the case of 

 the sarcinEB nor of the spirilla, and it is not always quite constant, 

 even in the true bacilli. In cheese I have frequently met with 

 aerobic, gelatin-hquefying, gas-producing plectridia which com- 

 paratively easily lost the abihty to form spores and thus were 

 not distinguishable from the Proteus bacteria. Thus, these 

 interesting forms not only form the transition between the spore- 

 forming and the non-spore-forming rods, but, as aerobic plec- 

 trida, between aerobic and anaerobic bacilH. In my opinion, 

 we generally know too httle as yet about the bacteria to be 

 warranted in definitely setting up famihes, and I therefore con- 

 sider we may safely put that off to the time when all the groups 

 of bacteria have been as thoroughly studied as the lactic acid 

 bacteria have recently been. 



