THE LAWS OF VARIABILITY. 59 



Islands, the offspring of the horses imported in 1764 

 hare already so mneh deteriorated in size and strength, 

 that they are unfitted for catching wild cattle with the 

 lasso ; so that fresh horses have to be brought for this 

 purpose from La Plata at a great expense. The reduced 

 size of the horses bred on both southern and northern 

 islands, and on several mountain-chains, can hardly have 

 been caused by the cold, as a similar reduction has oc- 

 curred on the Virginian and Mediterranean islands. 



It is scarcely possible to doubt that the 

 Page 56 



long-continued selection of qualities service- 

 able to man has been the chief agent in the formation of 

 the several breeds of the horse. Look at a dray-horse, 

 and see how well adapted he is to draw heavy weights, 

 and how unlike in appearance to any allied wild animal. 

 The English race-horse is known to be derived from the 

 commingled blood of Arabs, Turks, and Barbs ; but selec- 

 tion, which was carried on during very early times in 

 England, together with training, have made him a very 

 different animal from his parent stocks. 



u MAKING THE WOEKS OF GOD A MEBE MOCKEBY." 



Ori<nn of ^ e see ^^^ distinct species of the horse- 



Specie?, genus becoming, by simple variation, striped 

 page 130. on ^ e j e gg |-^ e a zebr^ or gtriped on the 



shoulders like an ass. In the horse we see this tendency 

 strong whenever a dun tint appears — a tint that ap- 

 proaches to that of the general coloring of the other spe- 

 cies of the genus. The appearance of the stripes is not 

 accompanied by any change of form or by any other new 

 character. We see this tendency to become striped most 

 strongly displayed in hybrids from between several of the 



