Bacillus. 27 



The genus Bacillus is very near to Bacterium ; Bac- 

 terium Lineola especially is very similar to single Bacillus 

 cells. But they can be distinguished by the fact that in 

 the longer Bacterium cells self-division has already begun, 

 while in equally long Bacillus cells no trace of division can 

 be perceived. 



The species are partly always motionless, partly spontaneously 

 motile, passing however at times into a condition of rest. The rod- 

 like cell lengthens itself by intercalary growth to about double its 

 original length, and then breaks up by a transverse division into two 

 daughter-cells, which often separate from one another, often also 

 remain united. Since the products of repeated divisions are arranged 

 end to end, there arise filaments which are often bent in a zigzag 

 fashion, often also straight, apparently unjointed, but the joints may be 

 brought into view by the application of staining materials. The de- 

 velopment and germination of the spores in Bacillus has been already 

 described. The demarcation of the different species is difficult in this 

 case also. 



A. ZYMOGENOUS SPECIES. 



39. B. subtilis (Ehrenberg), Cohn (I.e., p. 175). 

 Vibrio subtilis, Ehrenberg. 



Cells cylindrical, about 

 twice as long as broad, 

 as much as 6 /A long, fur- 

 nished with a flagellum at 

 each end. Usually several 

 united together in pseudo- X" o 

 filaments, which are like- Fig. i%. Bacillus subtms, with spores 



., ,, ., , (after Cohn). 



wise motile, flexile, and 



provided with a flagellum at each end. Spore-forming 

 rods three or four times as long as broad, isolated or united 

 in threads. Spores for the most part somewhat thicker 

 than the rods. (Figs. 18, 19, 200.) 



