CAUSES OF VARIATION. 93 



allowed to run wild on the bleak Falkland Islands, have reverted 

 in form and other characters to the type of the wild boar; not 

 so with those turned adrift on the rich soil of La Plata, or 

 Louisiana. A similar result took place in a pig of Natluisius, 

 seized at two months old with a disease of the digestive organs, 

 wliich permanently interfered with digestion and nutrition. 

 Though a highly bred Berkshire it assumed the long snout, the 

 coarse bristles, ridged back, flat sides and long legs of the wild 

 boar or unimproved breeds. 



So with the native cattle and sheep of the bleak mountains of 

 Scotland and "Wales, of Kerry and Brittany, which have degen- 

 erated to the smallest types of their kinds. The fat-tailed sheep 

 of Kurdistan is said to lose its fatty rump when removed to 

 Russian pastures. Tlie ponies of Norway and Sweden, of Ice- 

 land, Shetland, Wales, Devon, Brittany, Corsica and Sardinia 

 illustrate the same point. The horses running wild on the 

 Falkland Islands have degenerated to ponies within a compara- 

 tively recent period. 



Conversely a richer food increases bulk. Ayrshire cows re- 

 moved at four or five years old to the richer land of the Lothians 

 increase marvellously on the better keeping. The wonderful 

 excellence of the Durham cattle was no doubt rendered possible 

 by the rich pastures of the Ouse and Tees, and is now main- 

 tained by the artificial and forcing system of feeding so common 

 in such lierds. So with the English racer ; he is grained from 

 the very earliest age, and to an extent which would fail to be 

 remunerative in ordinary priced horses. At a month old he gets 

 a quarter of a peck daily, and the amount is steadily increased 

 with his growth. 



When we want to develop bone, muscle and vigor, this rich 

 and dry feeding is demanded, but where rapid growth and early 

 fattening only are desired, as in animals for the butcher, then a 

 softer and more aqueous but equally nutritive diet is essential. 



2d. Climate is not without its influence on variation. Cer- 

 tain races can't survive in particular climates ; they must change 

 their characters or die out. The Newfoundland dog has lost 

 most of his distinctive characters in England. He has not 

 hitherto been able to survive in India, nor at the Cape of Good 

 Hope. Greyhounds, pointers and bull-dogs rapidly lose their dis- 

 tinctive forms and mental qualities in India. The third genera- 



