74 ATLAS OF BACTERIOLOGY. 



brane, which usually remains colorless with ordinary 

 stains, is also stained and the bacteria appear to be 

 much thicker. Occasionally broad layers of the 

 membrane remain unstained, and the flagella are then 

 situated upon a narrow annular areola, separated from 

 the bacillus by a colorless zone (Zettnow, von Stock- 



a b c 



Fro. 7. Types of Flagella. a, Vibrio cholerse, a flagellum at one ex- 

 tremity; 6, bacterium syncyaneum, a bundle of flagella at one extrem- 

 ity, rarely on the side; c, bacterium vulgare, flagella arranged round 

 about. 



lin, A. Fischer). Unfortunately many of the meth- 

 ods used in staining lead forthwith to exfoliation and 

 degeneration of the flagella, so that their perfect ex- 

 hibition is often difficult. The above figure gives 

 a schematic representation of the three modes in 

 which bacteria are provided with flagella. 



In the cultures of bacteria which are rich in flagella, 

 Loffler first observed the occasional production of 

 peculiar, switch-like bodies, composed of flagella 

 which had fallen off or had been cast off and were 

 plaited into one another (vide Plate 47, Fig. II.). 



The power to produce flagella may be lost entire- 

 ly for generations ; whether permanently is s^till un- 

 known. Vide Micrococcus agilis, sarcina mobilis 

 (Lehmann and Neumann) . 



Ordinary vegetative increase of bacteria is effected 



