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may have been considered a special feature of the animal kingdom, 
the experiments of Mr. Darwin have proved that the roots of 
plants have not only a power of moving, (which they habitually 
do by a process Mr. Darwin describes as circumnutation) ; but 
that they possess a sensation which enables them to follow with 
unerring skill the line of least resistance. 
The primary reason for the circumnutation is the increased 
turgescence of the bladder-like cells with which the plant is built 
up; but why these walls are extended and the cell becomes turgid, 
is not so easy to explain. 
Mr. Darwin compares the rootlet tip to the brain; it does for 
the plant, what the great nerve-centre does for the animal, enabling 
it to transmit information from cell to cell. 
The folding of plants at night, and the folding up and closing 
of leaves, is effected by a similar action. 
Some plants which have been called ‘‘ insectiverous plants,” 
possess in a remarkable degree, a power of sensation and motion. 
The Drosera, a small plant growing on boggy ground, possesses 
curious viscid glandular hairs on the leaves. These glands have 
the power of absorption as well as secretion, and are very sensitive 
to various stimulants. A hair, when excited, not only sends 
some influence down its own tentacles, causing them to bend, but 
likewise to surrounding tentacles which become incurved. 
Animal substances placed on the discs, cause more prompt and 
energetic inflection than do inorganic bodies or mechanical irrita- 
tion. When a fly or piece of meat is placed upon the glandular 
hairs, they not only bend down and clasp it, but likewise dissolve 
it, and assimilate the nourishment. Under any mechanical 
stimulus they contract, but soon release their hold and expand 
again; on the other hand, with organic substances, they do not 
relax their hold. 
Physiologists believe that when a nerve is touched, it transmits 
its influence to other parts of the nervous system, and a molecular 
change is induced. By placing drops of Nitrogenous organic fluid 
on the leaves of the Drosera, they detect with unerring certainty 
the presence of Nitrogen. 
When the glands of the disc are irritated, they transmit some 
influence to the glands of the exterior tentacles, causing them to 
secrete more copiously, and the secretion becomes more acid; 
in this the plant behaves in the same way as the animal; a reflex 
action is here apparent. 
Another plant, the Venus Fly Trap, Dionea Wuseifera, 
possesses in a remarkable manner, the same properties of absorption 
of Nitrogenous substances, by the leaves, and the same kind of 
nervous powers. 
