366 PHARMACEUTICAL BOTANY 
Brownian movement the individual forms do not change their 
relative positions to any extent. 
The power of locomotion which certain bacteria possess is due 
to the possession by these forms of fine protoplasmic extensions 
from their bodies which are thought to pass from the cytoplasm 
through the cell wall into the surrounding liquid medium. 
These are called flagella or cilia. ‘They are endowed with the 
power of contractility, and through their vibratory motion the 
organism is enabled to propel itself through the fluid medium. 
The great majority of bacteria possessing flagella are the bacilli 
and spirilla. These flagella are rarely seen without special 
methods of treatment and staining. : 
Fic. 270. Fic. 271. 
Fic. 270.—Lophotrichous bacteria. Spirillum rubrum. (After Migula from 
Schmidt and Weiss and Marshall.) 
Fic. 271.—Peritrichous bacteria. Eberthella typhi. (Bacillus typhosus.) (After 
Migula from Schmidt and Weiss and Marshall.) 
The distribution of flagella varies in different forms of 
bacteria. Some possess a single flagellum at one pole and are 
called monotrichous. When a flagellum occurs at each pole, they 
are termed amphitrichous; when a tuft occurs at one pole, lopho- 
trichous; and when they occur over the whole cell, as in the case of 
the typhoid bacillus, peritrichous. 
The motility or non-motility of bacteria is best determined 
through the examination of a hanging drop. 
Nurrition.—Most bacteria derive their sustenance from 
organic substances. Those which obtain their nourishment from 
dead organic substances are termed saprophytic bacteria and those 
which obtain their nourishment from living organic material, 
parasitic bacteria. A number of the saprophytic forms will 
thrive both on living and dead organic matter and so are called 
