Cuar. XJ SUMMARY OF THE CHAPTER, 183 
no power, or only a very slight one, of inducing inflection. 
It should, however, be observed that curare, colchicine, and 
veratrine are muscle-poisons—that is, act on nerves having 
some special relation with the muscles, and, therefore, could 
not be expected to act on Drosera. The poison of the cobra 
is most deadly to animals, by paralysing their nerve-centres,* 
yet is not in the least so to Drosera, though quickly causing 
strong inflection. 
Notwithstanding the foregoing facts, which show how 
widely different is the effect of certain substances on the 
health or life of animals and of Drosera, yet there exists a 
certain degree of parallelism in the action of certain other 
substances. We have seen that this holds good in a striking 
manner with the salts of sodium and potassium. Again, 
various metallic salts and acids, namely those of silver, mer- 
cury, gold, tin, arsenic, chromium, copper, and platina, most 
or all of which 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 pro- 
pionic acids are highly poisonous, their ally, formic acid, is 
not so; and that, whilst certain vegetable acids, namely 
oxalic, benzoic, &., 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 pharmacopwia would be requisite to describe the diversified 
effects of various substances on Drosera.t 
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; 
* Dr. Fayrer, ‘The Thanatophidia 
of India,’ 1872, p. 4. 
t Seeing that acetic, hydrocyanic, 
and chromic acids, acetate of strych- 
nine, and vapour of ether, are poison- 
ous to Drosera, 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 rhyth- 
mic contractility of the yolk (of the 
ova of the pike) is not materiaily 
influenced by any of the poisons used, 
which did not act chemically, with 
the exception of chloroform and car- 
bonic 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. 
