274 



STRUCTURAL BOTANY 



but seems to be chiefly of a proteid nature. The cells 

 move actively, and their movements are now known to 

 be due to cilia which are attached to the protoplasm 

 and penetrate the wall (see Fig. 109, a, d). 



The whole interior of the cell is usually occupied by 



FIG. 109. Bacillus suUilis. 

 a, d, ciliated motile cell and 

 filament ; b, non-motile cells 

 and filament ; e, zoogloea, 

 during spore - formation ; c, 

 cells and filament with endo- 

 spores, from the zoogloea. 

 a-d, x!050. e, x 175. (After 

 A. Fischer.) 



FIG. 110. Bacillus megatherium, a, 

 chain of vegetative rods, each con- 

 sisting of two or more cells, but 

 septa not shown. Magnified 250. 

 p, four-celled rod, after treatment 

 with alcoholic solution of iodine ; 

 6, vegetative rods ; c-f, rods, show- 

 ing the formation of endo.spores ; 

 r, four-celled rod with ripe spores ; 

 g-^-g.j and h lt Ji 2 , spores swelling 

 before germination ; the mother cell- 

 walls disappear ; k-m, germination 

 of spores. All figures except a 

 magnified 600. (After De Bary.) 



the protoplasm. It is 



probable that a nucleus 



is present, though the minuteness of the cells renders 



its demonstration extremely difficult. 



For some time the Bacillus continues in the actively 

 swarming condition, multiplying abundantly by the re- 

 peated transverse division of the cells. After some days 

 the individuals begin to seek the surface of the liquid, 



