202 FIRST FORMS OF VEGETATION. 
Its filaments are elastic, rigid, and bristly, from 
three to six inches in length, about the size of a 
hog’s bristle, and knotted throughout at equal dis- 
tances with prominent swelling joints, like those of 
the bamboo cane. They spring from a tough car- 
tilaginous disk, so firmly applied to the rock as to 
require a very considerable force to detach it. It 
is impossible to convey in words, the same strong 
impression of fitness and perfection of contrivance, 
which a glance at the plant in its native haunts 
would produce. . It appears one of the most strik- 
ing examples of that compensatory adaptation of 
structure to requirements, which we observe more 
or less in all the lowest plants ; in the moss, which, 
considering its size, adheres with more tenacity to 
its growing place than the oak of centuries, that 
strikes out its roots over half an acre of ground ; 
and in the minute crustaceous lichen, apparently 
as hard as the rock upon which it is produced, 
over which the devastating storms of the Alpine 
summit sweep for years without inflicting upon it 
the slightest injury. The colour of the Lemania, 
when fresh, is of a fine deep olive-green; but it 
changes to black when dried and placed in the 
herbarium. The dilatations or gouty joints are 
owing to the development of the sporules within 
the fronds; and these may be squeezed out by being 
compressed between the fingers. The force with 
