BROWN I AN MOVEMENTS 



41 



ment" from Robert Brown (1773-1858), an English botanist, who 

 first observed them in 1827 when studying grains of pollen. Observa- 

 tions made by ingenious methods upon the Brownian movements 



FIG. 8. -Spirillum of Asiatic cholera, 

 showing single flagellum. (Kolle and 



FIG. 9. Spirillum volutans, showing 

 flagella at either end of the bacterium. 

 (Herzog.) 



of colloidal suspensoids are exactly what the kinetic theory indi- 

 cates would be the behavior of molecules of that size. Both dead 

 and non-motile bacilli show this movement as do also small particles 

 freely suspended in the liquid. However, many bacteria show a 



FIG. 10. Bacillus proteus vulgaris, showing numerous flagella around the entire body 



of the bacterium. (Herzog.) 



true independent motion and if watched the organism will be found 

 to change its position with relation to other organisms. This is 

 known as " vital movement." 



