CHAPTER X 



BACILt.1 : SPECIAL 



Before describing the various species of bacilli which in 

 man or animals, or both, are associated with infectious 

 disease we will describe the most common non-specific 

 bacilli, as, owing to their wide distribution, they not un- 

 commonly are found associated with the former. 



These are the most widely distributed species of bacilli : — 



(i) Bacillus subtilis, or hay-bacillus; (2) bacillus 

 mesentericus vulgatus ; (3) proteus vulgaris ; (4) proteus 

 Zenkeri ; (5) bacillus fluorescens liquescens ; and (6) bacillus 

 coli. 



I. Bacillus subtilis (hay-bacillus). — The elementary rods 

 are of various lengths from o'oo2 to o'oo6 mm., and are 

 about o'oo2 mm. in thickness. According to Cohn, 

 at a temperature of 21° C. division into two requires 

 about one hour and a quarter, at 35° C. only about twenty 

 minutes. 



The bacilli are capable of forming leptothrix filaments. 

 The bacilli when single are possessed of one flagellum, or 

 sometimes of two, one at each end. After division the 

 individual bacilli remain connected, each possessing a 

 flagellum at the free end. Each of them divides again 

 into four, so that a chain of four is formed. But they may 



