PLANTS KILLED BY POISON. 145 
exactly the effects of this poison on an animal. 
Prussic acid, one of the most terrible poisons 
known, also paralysed the poor plant; and, how- 
ever it might have been shaken, it refused to 
shew any of these signs of sensitiveness, which 
were previously manifest in it. Solutions of 
other poisons produced much the same effect on 
plants as they do upon animals; the poisoned 
trees soon perishing and withering away. 
Plants have also been exposed to different kinds 
of gases, and it has been found that those which 
destroy animal life, have the same effect upon 
that of vegetables. Perhaps one of the reasons 
why plants will not thrive in London may be, 
that the smoky filthy air of the metropolis acts as 
a sort of poison to these tender beings. Some- 
thing of this kind must be the cause of their 
drooping, withering, and dying, in spite of the 
greatest attention paid to them, as soon as ever 
they leave the pure and healthful atmosphere of 
the country for that of London. In Paris less 
impurity of the air exists, because there is little 
or no coal burnt, the fuel being chiefly wood and 
charcoal; and here we have often been struck 
with the freshness of the flowers in poor persons’ 
L 
