PROSPECTS FOR A NATURAL SYSTEM OF CLASSIFICATION OF BACTERIA 



dicates that also the flagellated rods find their origin in this primitive 

 group, the more so since the two typical modes of flagellation are al- 

 ready encountered. 



It seems only logical that the short Gram-negative polarly flagellated 

 rods, as for instance characteristic for the species of the genus Pseudo- 

 monas, owe their origin to a Gram-negative monoflagellated coccus.* 

 The polarity which arises from the attachment of a single flagellum 

 to the sphere may easily induce a polar deviation in the form of the 

 bacterium. In an analogous way the type of motility characteristic for 

 polarly flagellated organisms, viz., the rotation of the cell according to 

 its longitudinal axis, may well be responsible for a gradual deforma- 

 tion of the cell resulting in the comma or vibrio form. The numerous 



Fig. i . 



transitional forms between this morphological type and the spirillum 



forms leave no doubt as to the origin of the latter group. 



c. The appearance of more than one flagellum distributed over the 



* The same argumentation holds, of course, for the evolution of polarly flagellated 

 Gram-positive rods (the newly created genus Listerella) in relation to a motile Gram- 

 positive coccus. 



307 



