144 LIFE OF A TREE. 
In the lower animals we consider it a sign of 
instinct, if a creature avoids a certain kind of food 
which is calculated to injure it if swallowed. 
Shall we deny then instinct to the tree, when we 
find it behave almost precisely in the same man- 
ner? Dr. Daubeny has made a number of ex- 
periments on this subject. He watered plants 
for a long time with water containing in solution 
a chemical substance likely to injure them, but 
the plants refused to absorb the least trace of at; 
nor could it be found that any had got even into 
the inner tissues of the root. Even when watered 
with coloured water of an innocent kind, they 
seemed to have the power of absorbing the pure 
water and leaving the colouring matter behind. 
But, just as the instinct of the lower animals 
often fails them, and they will take food which 
may cause their death, so with trees and plants 
also. Experiments, for instance, have been made 
upon the sensitive plant by M. Macaire. A leaf 
of it was placed in a cold solution of opium, and, 
after remaining in it for a few hours, became quite 
insensible to the sharpest concussion, it would 
contract no more, it seemed overpowered as it 
were with sleep, and soon died. Now such are 
