224' DROSERA ROTUNDIFOLIA. Chap. IX. 



these substances are not poisonons and have 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, mercury, 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 j)oisonous 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 ta describe the 

 diversified efl'ects of various substances on Drosera. t 



* Dr. Fayrer, 'The Thanato- cyanic, and chromic acids, ace- 



phidia of India,' 1872, p. 4. tate of strychnine, and -vapour of 



t Seeing that acetic, hydro- ether, are poisonous to Drosera, 



