IN REFERENCE TO AGRICULTURE. 139 
(83.) The pursuits of the agriculturist and of the 
planter bring them more immediately into contact 
with the productions of nature; and hence they 
are more especially interested in understanding their 
qualities. It is not only necessary to be well ac- 
quainted with the different vegetables grown or 
reared for economic purposes, but to understand 
the cause of the injuries they are subject to; and 
then to devise efficient remedies for those injuries. 
Here, also, is a wide field open for improvement 
and for discovery, and in which no information is 
so practically useful as that afforded by natural 
history. We are continually hearing of the failure 
of crops, and of attendant ruin. Now, in nine 
instances out of ten, these devastations have origin- 
ated in the unusual abundance of some particular 
insect, which, from unknown causes, has appeared - 
in great numbers. We contend not that the know- 
ledge or the ingenuity of man could foresee such 
evils, or could totally counteract them; but expe- 
rience has shown how much may be done, in many 
cases, both in the way of prevention and of cure. 
To do this effectually, however, recourse must be 
had to natural history. The cause of the injury 
being ascertained, the habits of the insect must be 
studied in all its different stages. What will prove 
more or less efficacious in one of these stages, will 
be totally useless, or will increase the evil, in another. 
Hence arises the necessity of ascertaining names 
and species; without which, no effectual steps can be 
taken. 
(84.) If there required any striking fact to 
