45 
upon another. Some of you may have heard the story of the Boa 
Constrictor at the Zoological Gardens which swallowed its blanket. 
But the Boa was at any rate*right so far as this, that the blanket 
was an animal substance ; and probably the creature finding, on 
waking from its lethargy, this substance conveniently at hand, 
proceeded, without due consideration, to bolt it, the circumstances 
being such as could hardly occur in a state of nature. 
To return to the vegetable world. There is another plant 
well known to you all, the Sensitive Plant, which has the property 
of closing when it is touched. And there can be, I think, as little 
doubt that the plant does so for some reason essential to its own 
preservation, as that the Hedge-hog rolls itself into a ball for its 
- own protection. It may be that the Sensitive Plant secretes some 
juice or sap of which certain insects would like to partake, that 
the loss of this sap would be injurious to the plant, and that, 
_ therefore, it closes when touched to protect itself from depre- 
dation. The Sensitive plant is, at any rate, more humane in its 
_ mode of protecting itself than another plant, the AZentze/ia, which 
is also subject to the incursions of flies. This plant, as described 
by a French botanist, M. de Poison, is provided with a number 
of spikes, having their barbs set downwards. These are so thickly 
‘ placed that a fly has only room to insert his proboscis in the 
interstice between in order to get at the sap. But, on attempting 
‘to withdraw it, the proboscis is caught by the downward barb, and 
the result is that the unfortunate fly, thus hooked, generally ends, 
according to M. de Poison, by twisting off its own head in its 
frantic efforts to escape. 
_ There was a curious experiment performed lately by a French 
naturalist upon the Sensitive Plant. It was one of a series of ex- 
periments upon the nerves of plants, and I refer to it as illustrating 
a third point of identity between the animal and the vegetable 
world. You are aware that there is a class of substances called 
‘anesthetics—ether and chloroform for instance—which have the 
effect of paralysing the action of the nerves, and so destroying 
sensation in animals. You know that by means of this great and 
am 
beneficent discovery, a man may have the most terrible operation 
