274 THE BOOK OF A NATURALIST 
ficially apart in twenty different grooves the 
animals all revert to the one old simple groove in 
which they were first found by man. This much 
may then be said in favour of the dog: he is plastic. 
The plasticity is probably due to domestication, to 
the variety of conditions to which he is subjected 
as man’s companion in all regions of the globe, 
the selection which separates and preserves new 
varieties as they arise, and the crossing again of 
widely separated breeds. That he is plastic must 
be our excuse for determining to make the most 
we can of him to the complete exclusion of all 
other species, which might or might not prove 
plastic in the same degree. The fowl and pigeon 
are plastic, while the goose, guinea-fowl, pheasant, 
and peacock vary little or not at all. Nature may 
have better things than the dog, but we cannot 
guess her secrets, and to find them out by experi- 
ment would take a very long time. A bird in the 
hand, any bird, even a cock-sparrow, is better than 
all the birds of paradise that are in the bush. The 
other animals will serve us for sport while they last; 
and when they are gone we of this age shall be 
gone too, and deaf to whatever unkind things our 
posterity may say of us. The dog is with us, 
esteemed above all brutes, our favourite, and we 
shall give him no cause for jealousy. 
If we had him not, if we had never had him or 
had forgotten his memory, and were to go out 
again to select a friend and companion from the 
beasts of the field, the wild dog would be passed 
