212 SELECTION. Chap. XXI. 



Niata cattle cannot so well effect from their upturned jaws 

 and the shape of their lips ; consequently, if not attended to, 

 they perish before the other cattle. In Columbia, according 

 to Eoulin, there is a breed of nearly hairless cattle, called 

 Pelones ; these succeed in their native hot district, but are 

 found too tender for the Cordillera ; in this case, however, 

 natural selection determines only the range of the variety. 

 It is obvious that a host of artificial races could never survive 

 in a state of nature ; — such as Italian greyhounds, — hairless 

 and almost toothless Turkish dogs>, — fantail pigeons, which 

 cannot fly well against a strong wind, — barbs and Polish 

 fowls, with their -vision impeded by their eye wattles and 

 great topknots,— hornless bulls and rams, which consequently 

 cannot cope with other males, and thus have a poor chance 

 of leaving offspring, — seedless plants, and many other such 

 cases. 



Colour is generally esteemed by the systematic naturalist 

 as unimportant : let us, therefore, see how far it indirectly 

 affects our domestic productions, and how far it would affect 

 them if they were left exposed to the full force of natural 

 selection. In a future chapter I shall have to show that con- 

 stitutional peculiarities of the strangest kind, entailing 

 liability to the action of certain poisons, are correlated with 

 the colour of the skin. I will here give a single case, on the 

 high authority of Professor Wyman ; he informs me that, 

 being surprised at all the pigs in a part of Virginia being 

 black, he made inquiries, and ascertained that these animals 

 feed on the roots of the Lachnanthes tinctoria, which colours 

 their bones pink, and, excepting in the case of the black 

 varieties, causes the hoofs to drop off. Hence, as one of the 

 squatters remarked, " we select the black members of the 

 litter for raising, as they alone have a good chance of living." 

 So that here we have artificial and natural selection work- 

 ing hand in hand. I may add that in the Tarentino the 

 inhabitants keep black sheep alone, because the Hypericum 

 crispum abounds there ; and this plant does not injure black 

 sheep, but kills the white ones in about a fortnight's time. 6 



Complexion, and liability to certain diseases, are believed 



8 Dr. Heusinger, ' Woch^nschrift fiir die Heilkunde,' Berlin, 1846, s. 279. 



