FLAGELLA 



31 



There may be a single flagellum at one pole, when the arrangement is called mono- 

 trichate. There may be a single flagellum at each pole, the amphitrichate con- 

 dition. There may be a bunch of flagella at one pole, or more rarely at each, an 

 arrangement known as lophotrichate. The flagella may be arranged indiscrimin- 

 ately over the bacterial cell, when they are referred to as peritrichate (see Fig. 12). 

 The cells of any one flagellated species are characterized by one, and one only, 

 of these possible arrangements (see Fig. 13). 



CL 



Ci 



Fig. 13. — Diagram illustrating distribution of flagella. 

 a. Monotrichate. b. Amphitrichate. c and d. Lophotrichate. 



e. Peritrichate. 



Peritrichous flagellation is regarded by Pietschmann (1939) as due to the occur- 

 rence of subpolar flagella on a chain of undivided cells. We have ourselves seen 

 this phenomenon in the incompletely divided filamentous forms of monotrichate 

 organisms, but some exceedingly short cells have so many peritrichous flagella 

 that it would be absurd to postulate their multicellular nature merely to avoid 

 the assumption of peritrichous flagellation. 



Eecently Wei (1936) and Pijper (1938) have described the flagellation of the 

 typhoid bacillus as consisting of two conical spiral structures set up at an angle 

 at the side of the body (Fig. 14c). Pijper found that the two structures were 

 fused into one propelling " tail " organism in fast-moving bacilli (b in the figure). 

 He regards the two configurations of flagella as primary and secondary structures. 



