STRUCTURE AND CONSTITUENTS OF THE BACTERIAL CELL 29 
glycogen.^ Some stain black with osniic acid, indicatino; their fatty 
or Hpoidal nature, while others are probably complex phosphorus- 
containing compounds.- Not all of these varieties of granules are 
found in the same organism.'' Among the higher bacteria granules 
of sulphur or of iron are demonstrable respectively in the sulphur and 
the iron bacteria. 
Flagella.— All minute particles suspended in water or other fluids 
of low ^•iscosity are in constant motion. This motion, which is irregular 
and tremulous, was first described by Brown :^ it is variously termed 
Brownian movement, pedesis, or molecular movement.* Brownian 
m()^'ement may be rapid or slow, extensive or circumscribed, depending 
upim the nature of the particles and the composition and temperature 
of the fluid in which they are suspended. This is not true motility, 
even though each individual particle moves independently of the other 
particles in an irregular orbit, for the particles as a whole do not per- 
manently change their relative positions in quiet fluids. Dead bacteria 
and many living bacteria, notably the cocci, exhibit the Brownian 
movement. Many bacilli and spirilla, on the contrary, possess the 
Fig. 2. — Flagella. 1 and 6, peritrichic flagella; 2 and 4, monotrichic flagella; .3 and 5, 
lopotrichic flagella. 
power of independent motility, that is, they can progressively and 
permanently change their relative positions in space. Motile bacteria 
are provided with one or more long, delicate, contractile filaments— 
flagella— which are probably the organs of locomotion. These flagella 
cannot be demonstrated on living bacteria except possibly by dark- 
ground illumination, and ordinary staining reactions usually fail to 
re^'eal them.*^ Special staining methods show them clearly. They 
appear to arise from the cell membrane. '^ Their arrangement and 
number is varied among bacteria in general, but relatively constant 
for a particular variety of bacterium: they are thinner as a rule on 
younger bacterial cells, thicker on older organisms.^ A cholera vibrio 
has a single flagellum at one or both ends of the organism; in the 
1 Meyer, A.: Flora, 1899, 86, 428. 
2 Grimme: Centralbl. f. Bakteriol., orig., 1904. 36, .352. 
3 For literature see Marx and Woithe: Centralbl. f. Bakteriol., 1900, 28, 1, 3.3, 65, 
97. Krompecher: Ibid., 1901, 30, .385, 425. Gauss: Ibid., orig., 1902, 31, 92. 
" Edinburgh Phil. Jour., 1828, 5, 358; 1830, 8, 41. 
* See Phillip: Phys. Chem., 2d ed., 1913, p. 197 for discussion. 
« Reichert, K.: Centralbl. f. Bakteriol., orig., 1909, 51, 14, for excellent literature 
upon the demonstration of flagella. 
' Schaudinn: Arch. f. Protistenk., 1903, 2, 421. 
8 De Grandi: Centralbl. f. Bakteriol., orig., 1903, 34, 97. 
