CH. xvi] VIBRIO AND SPIRILLUM 405 



two fine spiral or wavy flagella. Owing to the curved shape 

 their movement is always characteristically corkscrewlike, 

 and therefore already by observing their movement in the 

 fresh specimen (hanging drop) they can be recognised as 

 comma bacilli or vibrios. This is particularly striking in 

 the S-shaped forms. 



The individual comma bacilli in stained and well-washed 

 specimens show the same distinction into sheath and proto- 

 plasm as was mentioned of the bacilli, and also the presence 

 of a vacuole in the middle of the individual comma bacilli 

 and the terminal easily stained collections of protoplasm. 

 Though in some species of bacilli, e.g., bacillus of glanders, 

 bacillus of diphtheria, there exist rods which are more or 

 less curved, they do not form spirals, and their curved 

 character is not permanent ; but in the true vibrios and 

 spirilla, however slight the curvature of some elements — 

 and in some species and under some media the curvature 

 of some of the elements is very slight indeed — they never- 

 theless are capable of forming spirals. Above all only 

 vibrios and spirilla form S-shaped forms, and the presence 

 of these is as typical a character as the formation of spirals 

 themselves. Anthrax bacilli growing on alkaline gelatine 

 assume occasionally a curved shape, while Finkler's spirilla, 

 or those found in noma and in cholera Asiatica, appear in 

 some media only to show the very slightest curve ; but from 

 subcultures of the above anthrax bacilli in broth or gelatine 

 the typical straight anthrax bacilli result, while of the above 

 spirilla subcultures made in broth, in gelatine, &c., the 

 typical spirilla will be the result. This shows that the first, 

 though they may occasionally become curved rods, are not 

 spirilla but bacilli, and the latter, though the individuals 

 may occasionally appear almost straight, are not bacilli but 

 spirilla. 



