CKOSS-BREEDING. 207 



longed to the Minorca in all probability the original 

 breed from which it was derived." 



The value of cross-bred animals for breeding-pur- 

 poses is diminished by this tendency to reversion, and 

 the consequent loss of the power of transmitting any 

 definite characters to their offspring. 



It is generally admitted that, in the cases in which 

 improvements are effected by crossing, the greatest 

 change is produced by the first cross, and that the im- 

 provement resulting from a repetition of the process 

 is uniformly slight. 



This would undoubtedly be the case from the prin- 

 ciples already presented : the greater the difference be- 

 tween the two parents, when one of them is prepotent 

 in the transmission of its characters, the greater would 

 be the resemblance of the offspring to the one, and 

 the wider the divergence from the characters of the 

 other parent ; and, as the resemblance of the parents 

 to each other would be gradually increased by succes- 

 sive crosses, the difference between the offspring and 

 the inferior parent would as gradually diminish 



It is claimed that the tendency to develop undesir- 

 able characters is increased by each successive cross ; 2 

 but the facts relating to this subject, in the history of 

 the breeds that have been established by crossing, have 

 not been recorded with sufficient exactness to furnish 

 conclusive proof of the correctness of this opinion. It 

 does not, however, appear to be improbable that such 



1 " Book of Poultry," p. 126. 



2 Journal of the Royal Agricultural Society, vol. xxiii., p. 352, vol. 

 xx., p. 296 ; Quarterly Journal of Agriculture, vol. i., p. 178, vol. vii., 

 p. 497 ; Sinclair's " Code of Agriculture," p. 95. 



