226 SELECTION. Chap. XXI. 



success. From the facts to be given, it will also be seen tliat 

 natural selection would powerfully affect many of our domestic 

 productions if left unprotected. This is a point of much 

 interest, for we thus learn that differences apparently of very 

 slight importance would certainly determine the survival of 

 a form when forced to struggle for its own existence. It may 

 have occurred to some naturalists, as it formerly did to me, 

 that, though selection acting under natural conditions would 

 determine the structure of all important organs, yet that it 

 could not affect characters which are esteemed by us of little 

 importance ; but this is an error to which we are eminently 

 liable, from our ignorance of what characters are of real value 

 to each living creature. 



When man attempts to breed an animal with some serious 

 defect in structure, or in the mutual relation of parts, he will 

 either partially or completely fail, or encounter much difficulty ; 

 and this is in fact a form of natural selection. We have 

 seen that the attempt was once made in Yorkshire to breed 

 cattle with enormous buttocks, but the cows perished so often 

 in bringing forth their calves, that the attempt had to be given 

 up. In rearing short-faced tumblers, Mr. Eaton says, 5 "I am 

 " convinced that better head and beak birds have perished in 

 " the shell than ever were hatched ; the reason being that the 

 " amazingly short-faced bird cannot reach and break the shell 

 " with its beak, and so perishes." Here is a more curious case, 

 in which natural selection comes into play only at long intervals 

 of time : during ordinary seasons the Niata cattle can graze as 

 well as others, but occasionally, as from 1827 to 1830, the plains 

 of La Plata suffer from long-continued droughts and the pasture 

 is burnt up ; at such times common cattle and horses perish by 

 the thousand, but many survive by browsing on twigs, reeds, &c. ; 

 this the 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 Colombia, accord- 

 ing 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, natural selection 



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: 







5 ' Treatise on the Almond Tumbler,' 1851, p. 33 



