< PLANTS. 
27 
a very surprising manner. The crupina, a species 
of centaury, has its seeds covered over with erect 
bristles, by which assistance it creeps and moves 
about in such a manner, that it is by no means to 
be kept in the hand. If you confine one of them 
between the stocking and the foot, it creeps out 
either at the sleeve or neck-band, travelling over 
the whole body. If the bearded oat, after harvest, 
be left with other grain in the barn, it extricates it- 
self from the glume ; nor does it stop in its pro- 
gress till it gets to the walls of the building. This 
progression is purely mechanical, and is thus ef- 
fected : every oat has a spiral awn or beard annexed 
to it, which contracts in wet and extends in dry 
weather. When the spiral is contracted it drags 
the oat along with it : the arista being bearded with 
minute hairs pointing downward, obliges the grain 
to follow; but when it expands again the beard can- 
not go back to its former place, on account of its 
roughness, which bending the contrary way pre- 
vents the return of the oat. 
The care which Nature takes to nourish her pro- 
ductions, to defend them from injury, and to sup- 
port those which are too weak to bear their own 
weight, is sufficiently obvious in many of the vege- 
table tribe. To enter fully upon this subject would 
be foreign to our purpose ; but a few instances may 
be selected that will serve as examples of the 
whole. 
There is no where a more manifest proof of de- 
