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rule caused inflection ; as did nineteen out of twenty-four 
organic and inorganic acids, the exceptions being gallic, tannic, 
tartaric, citric, and uric, none of which acted as poisons. The 
action of alkaloids and organic poisons was very various ; 
strychnine, digitaline, and nicotine are poisonous, and produce 
inflection, as does hydrocyanic acid very rapidly ; while morphia, 
hyoscyamus, atropine, veratrine, colchicine, curare, and dilute 
alcohol are not poisonous, and have no power, or only a very 
slight one, of inducing inflection. The vapours of chloroform, 
and sulphuric and nitric ether, act in a singularly variable 
manner, sometimes producing extraordinarily rapid inflection ; 
hut further experiments on this point seem required. 
The mode of transmission of the motor impulse from one 
gland to another is a very curious and intricate branch of the 
subject. From the facts already mentioned it would appear 
that the glands, together with the cells of the pedicel lying im- 
mediately beneath them, are the sole seat of the irritability or 
sensitiveness of the leaves ; and the impulse has to be trans- 
mitted down nearly the whole length of the pedicel before in- 
flection takes place. But this motor impulse is transmitted 
from the gland immediately excited to others which are not in 
contact with the exciting substance ; and in the tentacles thus 
indirectly excited the aggregation of the protoplasm always 
commences also in the cells immediately beneath the gland. 
Mr. Darwin terms this process a reflex action, and compares it 
to the irritation of a sensory nerve, by which, when an impres- 
sion is carried to a ganglion, some influence is sent back to a 
muscle or gland, causing movement or increased secretion. He 
believes that the motor impulse is not transmitted, at least ex- 
clusively, through the spiral vessels or the tissue immediately 
surrounding them, but through the cellular tissue, and more 
rapidly in a longitudinal than in a transverse direction. I am 
inclined to think, from experiments of my own, that it is pos- 
sible that, at least in some instances, the impulse may be trans- 
mitted, not through the tissue of the leaf at all, but through 
the viscid secretion ; as in some instances I have found tentacles 
on one leaf to be inflected by contact with excited tentacles 
belonging to another leaf, where there is nothing to cause in- 
flection in the first. One of the most remarkable circumstances 
connected with these phenomena is the fact that after leaves 
have been detached from the plant, they do not in any degree 
lose the power of inflection and aggregation of the protoplasm 
inherent in the tentacles for many hours or even days ; a strong 
indication that they possess some power of imbibing nutriment 
independent of the root. 
All that we have related so far would by no means prove a 
true process of digestion on the part of the sundew. It might 
