CH. x.] BACILLUS. 109 



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 

 separate again or may go on dividing, remaining united, 

 and thus forming a longer or shorter filament. Not all 



FIG. 45. FROM A CULTURE OF BACILLUS SUBTILIS (HAY-BACILLUS), WITH 

 COPIOUS FORMATION OF SPORES. 



1. Mass of spores embedded in hyaline matrix. 



2. Bacilli. 



3. Single bacilli containing each a spore : the sheath of the bacilli is well seen. 



Magnifying power about 700. 



bacilli possess the flagellum, many of them being for a time 

 in a resting state. 



The bacilli form a dense resistant pellicle on the 

 surface of the nourishing medium, and in this copious 

 spore-formation takes place. If shaken when growing in a 

 fluid, the pellicle falls to the bottom, and soon a new pellicle 

 is formed. 



Spore-formation is independent of any deficiency of nourish- 

 ing material. The spores are oval, bright, of about o'ooi to 

 0*002 mm. in length, and about 0*0006 to 0*001 mm. in 



