122 



GOOD FROM CROSSING. 



Chap. XVII. 



Now 



v 



even to suck, and when attempting to move could not walk straight inow 

 it deserves especial notice, that the two last sows produced by this Ion* 

 course of interbreeding were sent to other boars, and they bore several 

 litters of healthy pigs. The best sow in external appearance produced 

 during the whole seven generations was one in the last stage of descent • 

 but the litter consisted of this one sow. She would not breed to her sire 

 yet bred at the first trial to a stranger in blood. So that, in Mr Wright's 

 case, long-continued and extremely close interbreeding did not affect the 

 external form or merit of the young; but with many of them the general 

 constitution and mental powers, and especially the reproductive functions 

 were seriously affected. ' 



Nathusius gives 19 an analogous and even, more striking case : he im- 

 ported from England a pregnant sow of the large Yorkshire breed, and 

 bred the product closely in-and-in for three generations : the result was 

 unfavourable, as the young were weak in constitution, with impaired 

 fertility. One of the latest sows, which he esteemed a good animal, pro- 

 duced, when paired with her own uncle (who was known to be productive 

 with sows of other breeds), a litter of six, and a second time a litter of 

 only five weak young pigs. He then paired this sow with a boar of a small 

 black breed, which he had likewise imported from England, and which 

 boar, when matched with sows of his own breed, produced from seven to 

 nine young : now, the sow of the large breed, which was so unproductive 

 when paired with her own uncle, yielded to the small black boar, in the 

 first litter twenty-one, and in the second litter eighteen young pigs; so 

 that in one year she produced thirty-nine fine young animals ! 



injury is perceptible from moderately close interbreeding, yet, to quote the 



tTT /^V *"■/» y-vl *-N* ^v -L 1% /I # 1 J I M _ mm 



(who 



annual gold medal of the Smithfield Club Show for the best pen of pigs), 

 " Crosses answer well for profit to the farmer, as you get more con- 

 stitution and quicker growth ; but for me, who sell a great number of pigs 

 for breeding purposes, I find it will not do, as it requires many years to 

 ->et anything like purity of blood again." 20 





Before passing on to Birds, I ought to refer to man, though I 



am unwilling to enter on this subject, as it 



natural prejud 

 authors under 



3. It has mo 

 any points of 



21 



19 ' Ueber Eindvieh,' &c, s. 78. 



20 Sidney on the Pig, p. 36. See 

 also note, p. 34. Also Eichardson on 

 the Pig, 1847, p. 26. 



21 Dr. Dally has published an excel- 



is surrounded by 



been discussed by various 



Mr. Tylor 22 has shown 



have injured their cause by inaccu- 

 racies : thus it has been stated (Devay, 

 'Du Danger des Manages,' &c, 1862, 

 p. 141) that the marriages of cousins 

 have been prohibited by the legislature 



lent article (translated in the'Anthro- of Ohio; but I have been assured, in 



polog. Eeview,' May, 1864, p. 65), answer to inquiries made in the United 



criticising all writers who have main- States, that this statement is a mere 



tained that evil follows from con. fable 



sanguineous marriages. No doubt on 

 this side of the question many advocates 



22 See his most interesting work on the 

 ' Early History of Man/ 1865, chap. x. 





