Fig. 20. a, b, c, d, e, f . Aeromonas sp., Snieszko U-6. This typical culture 

 of Aeromonas was isolated from diseased fish. Old cultures showed a mixture 

 of polar flagellated individuals, some with the normal type of flagella and some 

 with the undulant type, as illustrated in a and b. One individual was found 

 with a normal and an undulant flagellum at the same pole (d). In young 

 cultures lateral flagella were found, both on individuals with a normal polar 

 flagellum and with an undulant polar flagellum, as illustrated in e and f. Note 

 the similarity of the lateral flagella in the two types. 



g, h, i, j. Aeromonas hydrophila, ATCC 7965. In old cultures were found in- 

 dividuals with a normal single polar flagellum, illustrated in g, and individuals 

 with a polar tuft of coiled flagella, illustrated in h. In young cultures individuals 

 with lateral flagella of short wavelength were found as illustrated in i and j. 



k, 1. A. liquefaciens, Kluyver L-417. Old cultures of this strain showed 

 normal single polar flagella only, while young cultures showed many individuals 

 with peritrichous flagellation. In this strain the polar and lateral flagella were 

 of the same wavelength. 



m. A. formicans, Pivnick. Normal polar monotrichous flagellation. Both 

 old and young cultures showed only this type of flagellation. This organism 

 may not be a pathogen for cold bloocled animals. 



n. Aeromonas sp., Snieszko, U-23. The polar flagellum illustrated is unusual 

 in that the wavelength gets progressively longer from the soma out. This type 

 of flagellum was seen frequently in several strains of Aeromonas but is very 

 rare in other bacterial genera. 



o. Aeromonas (?) sp. This culture was received as A. liquefaciens, Kluyver 

 L-418. It is physiologically typical of Aeromonas and may be a morphological 

 mutant but definite evidence to this effect is lacking. All individuals in the 

 culture showed the coiled peritrichous flagellation. Morphologically and physio- 

 logically this organism is very similar to a nonpigmented Serratia. 



g, h, i, j, k, 1, o. From E. Leifson, and R. Hugh, /. Bacteriol. 65, 263-271 

 (19.53). 



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