32 THE MORPHOLOGY OF BACTERIA 



theory," which assumes that transverse fission, the more economical 



process both with respect to amount of material and expenditure 



of energy, holds universally for bacteria, as has previously been 

 maintained. 



F. CELL GROUPING. 



In Bacilli and Spirilla, where septation typically occurs at right 

 angles to the long axis of the organism, it is obvious that no geometrical 

 arrangement of cells is possible other than the formation of chains of 

 rods or of spirals if the individual organisms remain adherent. The 

 cocci, on the other hand, are spherical and have no longer or shorter 

 axis, consequently a definite sequence of septation in one, two or 

 three planes of space can give rise to (1) chains of cocci, if the plane 

 of septation is always in one plane of space; (2) groups of four cocci, 

 if septation takes place alternately in two planes of space; or (3) in 

 packets of cocci, if septation is alternate in three planes of space. 

 Many cocci do not exhibit a definite sequence of planes of septation. 



G. CLASSIFICATION OF BACTERIA. 



Relation to Higher Plants. The position of Bacteria in the Plant 

 Kingdom is indicated in the following table : 



Plant Kingdom. 



A complete natural classification of bacteria is impossible at the 

 present time. The monotony of form observed in this group of 

 organisms merely suffices to classify them into three great divisions: 

 Cocci, Bacilli, and Spirilla. Further subdivision into groups which 

 are potentially families, genera and species is accomplished by arrang- 



