are highly poisonous to animals, are equally so to Drosera. But it is a
singular fact that the chloride of lead and two salts of barium were
not poisonous to this plant. It is an equally strange fact, that,
though acetic and propionic acids are highly poisonous, their ally,
formic acid, is not so; and that, whilst certain vegetable acids,
namely oxalic, benzoic, &c., are poisonous in a high degree, gallic,
tannic, tartaric, and malic (all diluted to an equal degree) are not
so. Malic acid induces inflection, whilst the three other just named
vegetable acids have no such power. But a pharmacopoeia would be
requisite to describe the diversified effects of various substances on
Drosera.**
* Dr. Fayrer, The Thanatophidia of India, 1872, p. 4.
** Seeing that acetic, hydrocyanic, and chromic acids, acetate of
strychnine, and vapour of ether, are poisonous to Drosera, [[page 225]]
it is remarkable that Dr. Ransom ( Philosoph. Transact. 1867, p. 480),
who used much stronger solutions of these substances than I did, states
that the rhythmic contractility of the yolk (of the ova of the pike)
is not materially influenced by any of the poisons used, which did not
act chemically, with the exception of chloroform and carbonic acid. I
find it stated by several writers that curare has no influence on
sarcode or protoplasm, and we have seen that, though curare excites
some degree of inflection, it causes very little aggregation of the
protoplasm.) [page 226]
Of the alkaloids and their salts which were tried, several had not the
least power of inducing inflection; others, which were certainly
absorbed, as shown by the changed colour of the glands, had but a very
moderate power of this kind; others, again, such as the acetate of
quinine and digitaline, caused strong inflection.
The several substances mentioned in this chapter affect the colour of
the glands very differently. These often become dark at first, and then
very pale or white, as was conspicuously the case with glands subjected
to the poison of the cobra and citrate of strychnine. In other cases
they are from the first rendered white, as with leaves placed in hot
water and several acids; and this, I presume, is the result of the
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