REDUCTION OF VARIABILITY. 125 



pig-Sty on the heath, a thriving colony of rats will be established 

 in a few months. 



We marvel at the adaptative change of colour of the alpine 

 hare and of the stoat with the seasons. It is more than possible 

 that animals which are now inhabiting parts of the world where 

 snow never falls, will react in the same way to a low temper- 

 ature at the time of the autumn moult. 



If we notice some plant or animal, beautifully adapted to the 

 circumstances under which we find it living we may iniagine, 

 how it has been subjected to those same circimistances for 

 untolld generations, and how it has gradually adapted itself 

 to those conditions. But we might be deluding ourselves. It 

 may very well be that only after the organism became what it 

 is now, it foimd the circumstances imder which it now exists, in 

 other words, it is possible that an organism finds the environ- 

 ment to which it happens to be adapted, rather than adapting 

 itself to an environment. There is nothing which so binds an 

 organism to its environment as just its ability to live in it. 



We want to illustrate this point. It seems as if cultivated 

 plants and animals are being bred more and more closely toward 

 an ideal state of usefulness, in some fixed direction. In most cases 

 this is true. Evidently, breeds of milk-producing cattle are bred, 

 or rather should always be bred, with an eye to their product- 

 iveness, and they are in point of fact getting more and more 

 adapted to their circumstances, to the economical system into 

 which they fit. But even in the case of cultivated species, it is 

 possible to point out instances in which particular species are 

 now ex-ellently fitted for the use to which they are put, to the 

 environment in which they must Uve, whereas we know for 

 certain that they were not developed in these circumstances, 

 and to fit these uses. 



The Airedale terrier, formerly known as the Waterside ter- 

 rier is a case in point. It was bred by rat-catchers and poachers 

 as a useful companion, loving a fight, inteUigent enough to 

 drive a hare into the poacher's net without giving tongue, 

 unafraid of water, and game after rats. When the craze for 



