1881.] The Reasoning Faculty of Animals. 607 
clear evidence of reasoning powers, and of the facuJty of adapting 
means to ends. 
Again we are told that many insects lay their eggs upon the 
leaves of certain plants, upon which the larve feed, and upon no 
others, and it is pointed out as a case in which the Almighty has 
endowed the creature with an instinctive knowledge of the plant. 
But why should it be so? The white butterfly lays its eggs upon 
the cabbage, and the larve feed upon its leaves. What right 
have we to say that the butterfly does not know the cabbage? 
There may be something about that plant agreeable to her olfac- 
tory nerves; which induces her to alight and deposit her eggs. 
Or it may be that in ancient days, and must have been, that the 
butterfly deposited her eggs upon any plant indiscriminately. 
If those that fed upon the cabbage throve better than those on 
some other plant, they would be preserved in the struggle for 
existence, and leaving more descendants than their rivals, would 
thus transinit the habit of frequenting more and more the cabbage 
plant. Perhaps at the time some species of insects originated, the 
ancestor of all deposited her eggs upon any plant most con- 
venient. All may not have been suitable, but the larve throve 
on those that were, and frequented the same plant afterwards ; 
and thus in feeding on different plants and leading different lives, 
the one original species became differentiated into distinct but — 
allied species, 
The instinct which induces the cuckoo to lay her eggs in the 
nests of other birds, can be shown to have arisen in much the 
Same manner as those to which we have referred. Mr. Darwin 
gives an excellent account of how the instinct might be developed. 
He says: “ Now let us suppose that the ancient progenitor of the 
European cuckoo, had the habits of the American cuckoo, and 
that she occasionally laid an egg in another bird’s nest. If the 
old bird profited by this occasional habit through being able to 
migrate earlier, or through any other cause; or if the young 
were made more vigorous by advantage being taken of the mis- 
taken instinct of another species, than when reared by their own 
Mother, encumbered as she could hardly fail to be by having 
gs and young of different ages at the same time; then the old 
birds or the fostered young ones would gain an advantage. And 
analogy would lead us to believe, that the young thus reared, 
Would be apt to follow by inheritance the occasional and abber- 
