306 



THE CROSSING, &C, OF CATTLE, ET AL. 



proving. But, after (say) twenty, or thirty generations 

 of interbreeding, between (say) brothers and sisters, 

 the evil will begin to manifest itself; unless, the ca- 

 pacity for reversion, in these slightly deteriorated parts, 

 has been able to outstrip the exacerbation, consequent 

 upon the community of defects, in the individuals 

 paired; or unless the brothers and sisters were dis- 

 similar in these little points,— which would not be 

 unlikely. 



When regarded by themselves, it is apparent, from 

 what is known of the diversity'prevailing among the 

 different breeds of cattle, that the individuals vary 

 much from what can be estimated to Be the true ratio 

 of the development of the characters of the said 

 species. But, such, departure from the true type, im- 

 plied from their diversity, seems scarce worthy of 

 thought, when the great disproportion of Pigs, Pigeons, 

 and Fowls (especially of the high fancy breeds thereof), 

 recurs to the mind. 



Again Darwin says, respecting Cattle : 



" Mr. Bates's herd was esteemed the most celebrated 

 in the world. For thirteen years, he bred most * 

 closely in-and-in ; but, during the next seventeen 

 years, though he had the most exalted notion of the 

 value of his own stock, he thrice infused fresh blood 

 into his herd; it is said, that he did this, not to im- 

 prove the form of his animals, but on account of their 

 lessened fertility. Mr. Bates's own view, as given by 

 a celebrated breeder, was that ' to breed in-and-in from 

 a bad stock, was ruin and devastation ; yet, that the 

 practice may be safely followed, within certain limits, 

 when the parents, so related, are descended from first- 



