PLANTS. 
25 
the most familiar instances of which (among a great 
number) are the thistle and dandelion. These have 
downy appendages with which they may be seen 
floating in the air in great quantities, and are thus 
carried by the current to a considerable distance 
from the parent plant. Some are furnished with 
hooks, by which they adhere to the coats of animals, 
and are carried by them to a distance; while others 
are dispersed by birds, who carry them to different si- 
tuations, where they are deposited and afterwards take 
root. It must not be omitted, that in many genera 
the seeds are dispersed with violence by the sudden 
bursting of the vessels which contain them. There 
is a remarkable instance of this, and one which we 
may command at pleasure, in the different species 
of fern. These plants, to the casual observer, ap- 
pear to be without seeds ; but, upon examining the 
under surface of their leaves, rows of conical dots 
may be seen, and in each little protuberance many 
a future fern is concealed. These little cones are 
covered by a very fine, thin, semitransparent skin, 
which bursts open before the seeds are ripe. The 
seeds themselves are enclosed within a globular 
capsule, which is surrounded by an elastic cord. 
When the seeds are ripe, the cord endeavours to be- 
come straight, and, by its elasticity, tears open the 
capsule and scatters the seeds. These are very 
minute objects, and hardly visible to the naked eye; 
but, by the assistance of a good single microscope 
and reflecting speculum, they may be clearly de- 
tected. In the months of September and October, 
