214 
INSTINCT. 
Chap. VII. 
crossed. Thus it is known that a cross with a bull-dog 
has aflfected for many generations the courage and obsti¬ 
nacy of greyhounds; and a cross with a greyhound has 
given to a whole family of shepherd-dogs a tendency to 
hunt hares. These domestic instincts, when thus tested 
by crossing, resemble natural instincts, which in a like 
manner become curiously blended together, and for a 
long period exhibit traces of the instincts of either 
parent: for example, Le Eoy describes a dog, whose 
great-grandfather was a wolf, and this dog showed a 
trace of its wild parentage only in one way, by not 
coming in a straight line to his master when called. 
Domestic instincts are sometimes spoken of as actions 
which have become inherited solely from long-continued 
and compulsory habit, but this, I think, is not true. 
No one would ever have thought of teaching, or pro¬ 
bably could have taught, the tumbler-pigeon to tumble,—• 
an action which, as I have witnessed, is performed by 
young birds, that have never seen a pigeon tumble. 
We may believe that some one pigeon showed a slight ten¬ 
dency to this strange habit, and that the long-continued 
selection of the best individuals in successive generations 
made tumblers what they now are; and near Glasgow 
there are house-tumblers, as I hear from Mr. Brent, 
which cannot fly eighteen inches high without going 
head over heels. It may be doubted whether any one 
would have thought of training a dog to point, had not 
some one dog naturally shown a tendency in this line; 
and this is known occasionally to happen, as I once 
saw in a pure terrier: the act of pointing is probably, 
as many have thought, only the exaggerated pause of 
an animal preparing to spring on its prey. When the 
first tendency to point was once displayed, methodical 
selection and the inherited effects of compulsory training 
in each successive generation would soon complete the 
