18 



MORPHOLOGY. 



ical, rod, thread, or spiral in form, with no organs except 

 flagella which are used for locomotion. Vegetative increase is 

 by transverse, very rarely by longitudinal division. A series 

 of varieties form roundish, endogenous resting spores ; in 

 others there have been, or asserted to have been, observed 

 conidia-like formations (arthrospores). Other means of 

 propagation have not been observed. 



Bacteria occur, so far as we know, only in the following 

 forms, which were first perfectly named by H. Buchner: 



G O C 

 a \ 



\e/ 



\d X 



Fig. 1. — Forms of bacteria (after Buchner). 



Individual Growth Forms. 



Spherical form (Kugelform) (a). 



Oval form (Ovalform) (6): length, at most 2 X the width. 

 Short rods (Kurzstabchen) (c): length, 2-4 X width. 

 Long rods (Langstabchen) (d): length, 4-8 X width. 

 Thread forms (Fadenform) (e). 



Half screw (Halbschraube) = comma (/): a very short segment of a 

 screw ; at most, half the turn of a screw. 



Short screw (Kurzschraube) (g): a short turn of a screw. 



