been brought home
as puppies from countries, such as Tierra del Fuego and Australia, where
the savages do not keep these domestic animals. How rarely, on the other
hand, do our civilised dogs, even when quite young, require to be taught
not to attack poultry, sheep, and pigs! No doubt they occasionally
do make an attack, and are then beaten; and if not cured, they are
destroyed; so that habit, with some degree of selection, has probably
concurred in civilising by inheritance our dogs. On the other hand,
young chickens have lost, wholly by habit, that fear of the dog and cat
which no doubt was originally instinctive in them, in the same way as it
is so plainly instinctive in young pheasants, though reared under a hen.
It is not that chickens have lost all fear, but fear only of dogs and
cats, for if the hen gives the danger-chuckle, they will run (more
especially young turkeys) from under her, and conceal themselves in
the surrounding grass or thickets; and this is evidently done for the
instinctive purpose of allowing, as we see in wild ground-birds, their
mother to fly away. But this instinct retained by our chickens has
become useless under domestication, for the mother-hen has almost lost
by disuse the power of flight.

Hence, we may conclude, that domestic instincts have been acquired and
natural instincts have been lost partly by habit, and partly by man
selecting and accumulating during successive generations, peculiar
mental habits and actions, which at first appeared from what we must in
our ignorance call an accident. In some cases compulsory habit alone
has sufficed to produce such inherited mental changes; in other cases
compulsory habit has done nothing, and all has been the result of
selection, pursued both methodically and unconsciously; but in most
cases, probably, habit and selection have acted together.

We shall, perhaps, best understand how instincts in a state of nature
have become modified by selection, by considering a few cases. I will
select only three, out of the several which I shall have to discuss in
my future work,--namely, the instinct which leads the cuckoo to lay her
eggs in other birds' nests; the slave-making instinct of certain ants;
and the comb-making power of the hive-bee: these two latter instincts
have generally, and most justly, been ranked by naturalists as the most
wonderful of all known instincts.

It is now commonly admitted that the more immediate and final cause
of the c