438 Pork Production 



characters making up the individual. A character may 

 lie latent, or be covered up as it were, for five, ten, or any 

 number of generations and then make its appearance. 

 When two animals are mated each of which have the same 

 character latent, some of the offspring will show the char- 

 acter developed. Reversion, in other words, is merely 

 the expression of a character which was always present in 

 some of the ancestors, but which was latent or not devel- 

 oped. 



Incidentally these facts make plain the fundamental 

 and important principle that the individual appearance 

 of an animal only partially or imperfectly represents his 

 breeding possibilities. In other words, the individuality 

 of an animal is not altogether a safe criterion of his breed- 

 ing ability. It also explains why two individuals with 

 exactly the same pedigree may differ materially in breeding 

 qualities. 



The older a breed, or the more carefully it has been bred 

 within certain lines, the fewer will be the number of latent 

 characters present. Reversions or the appearance of the 

 unexpected become less frequent, therefore, in old well- 

 established herds than in those in which out-crossing or 

 cross-breeding has been resorted to. The selection of 

 breeding stock within rather definite and narrow limits 

 tends ultimately to reduce reversions, while out-crossing 

 has the opposite effect of bringing about the conditions 

 which result in variations and so-called reversions. 



The second kind of variations are those which result 

 from differences in the conditions under which the indi- 

 viduals have been developed. They are sometimes called 

 acquired characters. Variations of size and vigor which 

 result from differences of feeding and care are most com- 

 mon. Two pigs may have an inheritance equally good, 



