98 GOOD FROM CROSSING. Chap. XVII. 



the following account of the wild cattle kept in the Duke's park in 

 Lanarkshire, which is about 200 acres in extent. The number of 

 cattle varies from sixty-five to eighty ; and the number annually 

 killed (I presume by all causes) is from eight to ten ; so that the 

 annual rate of increase can hardly be more than one in six. Now 

 in South America, where the herds are half-wild, and therefore 

 offer a nearly fair standard of comparison, according to Azara the 

 natural increase of the cattle on an estancia is from one-third to 

 one-fourth of the total number, or one in between three and four ; 

 and this, no doubt, applies exclusively to adult animals fit for con- 

 sumption. Hence the half-wild British cattle which have long 

 interbred within the hmits of the same herd are relatively far less 

 fertile. Although in an unenclosed country like Paraguay there 

 must be some crossing between the different herds, yet even there 

 the inhabitants believe that the occasional introduction of animals 

 from distant localities is necessary to prevent " degeneration in size 

 and diminution of fertility." 10 The decrease in size from ancient 

 times in the Chillingham and Hamilton cattle must have been pro- 

 digious, for Professor Eiitimeyer has shown that they are almost 

 certainly the descendants of the gigantic Bos primigenius. No 

 doubt this decrease in size may be largely attributed to less favour- 

 able conditions of life ; yet animals roaming over large parks, and 

 fed during severe winters, can hardly be considered as placed under 

 very unfavourable conditions. 



With Sheep there has often been long-continued interbreeding 

 within the limits of the same flock ; but whether the nearest rela- 

 tions have been matched so frequently as in the case of Shorthorn 

 cattle, I do not know. The Messrs. Brown during fifty years have 

 never infused fresh blood into their excellent flock of Leicesters. 

 Since 1810 Mr. Barford has acted on the same principle with the 

 Foscote flock. He asserts that half a century of experience has 

 convinced him that when two nearly related animals are quite 

 sound in constitution, in-and-in breeding does not induce dege- 

 neracy ; but he adds that he " does not pride himself on breeding 

 from the nearest affinities." In France the Naz flock has been bred 

 for sixty years without the introduction of a single strange ram. 11 

 Nevertheless, most great breeders of sheep have protested against 

 close interbreeding prolonged for too great a length of time. 12 The 

 most celebrated of recent breeders, Jonas Webb, kept five separate 

 families to work on, thus " retaining the reqiusite distance of rela- 

 tionship between the sexes;" 13 and what is probably of greater 

 importance, the separate flocks will have been exposed to somewhat 

 different conditions. 



10 Azara, ' Quadrupedes du Para- flock, ' Bull, de la Soc. d'Acclimat.,' 

 guay,' torn. ii. pp. 354, 368. 1860, p. 477. 



11 For the case of the Messrs. 12 Nathusius, ' Eimlvieh,' s. 6.3; 

 Brown, see 'Gard. Chronicle,' 1855, Youatt on Sheep, p. 495. 



p. 26. For the Foscote flock, 'Gard. I3 'Gard. Chronicle,' 1861, o. 631 



Chron.,' 1860, p. 416. For the Naz 





