58 HEREDITY AND EUGENICS 



thenon, having the same short cock-thrappled neck, 

 hairy jowl, and horizontal head. As regards colour, 

 bays and browns were most numerous, then chest- 

 nuts, a few blacks, no greys, one probable red roan, 

 one pure white, many piebald, and many '* bluish 

 mouse colour "* often wdth a black stripe along 

 the back, but none with black lines around the 

 legs. 



The striking features in the history of these horses 

 appear to be ( i ) the complete reversion to an ancestral 

 condition, with change of form and decrease in size; 

 (2) the large number of colour varieties. Mere in- 

 breeding will not account for the former. The colour 

 varieties may, perhaps, all have been represented in 

 the germ plasm, the piebald and bluish colours being 

 extremelv old. Piebald horses have existed in all 

 ages. According to Gilpin, the}^ are depicted on the 

 most ancient coins of China and w^ere contemporary 

 with the siege of Tro\^, being still seen feral in Northern 

 Italy. They have also appeared in Patagonia and 

 among the horses of the North American Indians. 

 The structural changes involved in the reversion of 

 these Sable Island ponies must have resulted in some 

 w^ay from the rigorous conditions. How the environ- 

 ment acts in such cases is not clear. It ma}^ be parth' 

 by direct inhibition of development, and partly by 

 selection of smaller varieties requiring less food. It 

 may also involve the reappearance as fresh mutations 

 of conditions which had previously been selected out 

 of the germ plasm by the action of man. The small 

 human races in some inhospitable climates may, 

 perhaps, be accounted for in a similar wa}^ — i.e., by 

 the selection of variations, sometimes negative, which 

 made survival more likely, as well as by the direct 

 inhibiting effects of unfavourable conditions. But 



* This " Phrygian cerulean blue of Homer " is scarcely known 

 among modern domestic breeds. 



