HEREDITY: MEANING AND INFLUENCE 27 



show that at a previous period there was a red ancestor. 

 This red color was really hereditary, but lay dormant, or 

 latent, as it is termed, for some generations, and then cropped 

 out. The stockman usually calls this a "sport." Scientists 

 speak of it as a "mutation." The important point, how- 

 ever, is that this character really was inherited from gen- 

 eration to generation, but did not appear until certain con- 

 ditions were favorable. Many similar cases might be cited 

 that have caused much comment among stockmen. In this 

 connection, it may be noted that mutation occurs less fre- 

 quently with old, well-established breeds than with those 



Figure 7. A good example of fecundity, a Duroc-Jersey sow and litter of 14 

 pigs. Photograph from Ohio Experiment Station. 



not so old and less under natural than under artificial con- 

 ditions. It is also important to remember that sometimes 

 mutation results in valuable variations from the parent type. 

 Instances have occurred where intelligent breeders have 

 recognized the value of such a "sport," and have succeeded 

 in reproducing it through successive generations, until it 

 became a fixed breed feature. More than one hornless breed 

 of cattle and sheep have been founded by the unexpected 

 appearance of a polled animal in a horned herd. This 

 anomaly applies especially to Polled Jersey, Polled Hereford, 



