Chap. Y1IL] IN DOMESTICATED ANIMALS. 327 



become mingled, is well shown when different breeds of 

 dogs are crossed. Thus it is known that a cross with a 

 bull-dog has affected for many generations the courage 

 and obstinacy of greyhounds ; and a cross with a grey- 

 hound 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 is not true. USTo one 

 would ever have thought of teaching, or probably 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 tendency 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 pre- 

 paring to spring on its prey. When the first tendency 



