32 



MORPHOLOGY 



In dead bacilli the primary structures disperse into fine threads which he regards 

 as post-mortem artefacts, not as peritrichous flagella which in life form a functional 

 unit. It is, however, legitimate to regard the peritrichous flagellum as the primary 

 structure, for there are analogous cases of functional unity of structures that are 



B C 



Fia. 14. — Bacterial Flagella. 



A. Electron micrograph of CI. tetani, showing protoplasm, cell wall and flagella ( X 22,000). 



B. and C. Dark-ground photomicrographs of living Salm. typhi ( X 5000). 



(From photographs kindly supplied by Dr. Stuart Mudd and Dr. A. Pijper.) 



made up of morphologically separate flagella. The undulating membrane of 

 certain ciliate infusoria, for instance, consists of a fine row of ciUa which can during 

 life be separated by mechanical means into single cilia all moving in an unco- 

 ordinated manner (Maier 1903, Chambers and Dawson 1925). 



