GENERAL MORPHOLOGY AND PHYSIOLOGY. I2Q 



groups, distinguished by the formation of endo- 

 spores in the one, and of arthrospores in the other. 

 In the process of fission the cell first increases in 

 size, and a transverse septum forms from the cell-wall, 

 dividing the internal protoplasm into two equal 

 parts ; these may separate and lead an independent 

 existence, or remain linked together. In chains of 



FIG. 52. BACILLUS MEGATERIUM. 



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



b. Two active rods. 



d to/". Successive stages of spore-formation. 

 h and /. Successive stages of germination. 



[After DeBary.] 



cocci the individual cells are easily visible and 

 distinct, but in the thread-forms resulting from the 

 linking together of rods, as in the anthrax bacillus, 

 the composition of the thread is only demonstrated 

 by the action of reagents. 



Endospore formation may be conveniently studied 

 in Bacillus ant hr acts > Bacillus megaterium, or Bacil- 

 lus subtilis. The protoplasm becomes granular, 



9 



