3 io 



BACTERIOLOGY. 



is formed of rows of rods lying closely together. 

 These rods can be observed to divide into short 

 rods and cocci. Spore-formation occurs in two 

 stages of development, viz., in the cocci and in the 

 short rods. A cultivation is obtained by exposing 

 slices of boiled carrot, slightly moistened, to the 

 air at the temperature of the room. 



Bacillus megaterium, De Bary. Large rods 

 2*5 /u< wide, and four to six times as long. They 



FIG. 120. BACILLUS MEGATERIUM. 



a. A chain of rods, X 250. The rest X 600. 



b. Two active rods. 



d\.of. Successive stages of germination. 

 h and /. Successive stages of germination. 

 [After De Bary.] 



are usually somewhat curved. Transverse division 

 occurs, each segment attaining the length of the 

 original rod. In the fresh state they appear non- arti- 

 culated, but when treated with a dehydrating agent 

 (tincture of iodine, alcohol), they are seen to be 

 composed of short segments. The rods are motile, 

 and form irregular chains, of a disjointed appear- 



