UNIT CHARACTERS lOi 



■> not a good one. They are latent only in the sense that they 

 re not evident except as they outcrop in succeeding generations, 

 when, with other blood lines, the new combinations become 

 sufficiently strong or otherwise favorable to bring them out. 

 They are not latent in the sense that their presence cannot be 

 suspected. If we examine carefully all the unit characters in 

 any race, we shall know positively what characters will be pos- 

 sessed by the descendants, but as to which will develop and give 

 visible evidence of their presence in any particular individual 

 we cannot predict. We shall see later, however, that if both 

 sire and dam are black, knowing nothing about other ancestry, 

 the offspring will stand even chances of being black also. If all 

 the grandparents, however, were red, the offspring, even of 

 black parents, would stand one chance in four of being red ; or, 

 what is the same thing, one fourth of all such offspring would 

 be red and one half black, with the other one fourth unknown. 



Characters dominant and characters recessive. Some charac- 

 ters are dominant, that is, strong and easily seen, while others 

 are difficult of detection or easily covered up and obscured by 

 stronger ones. Thus, in flowers, pink is easily lost in red ; light 

 blue, in purple ; or yellow, in green. Small size is obscured by 

 large size, and, in general, certain characters are much more 

 readily seen than others. Those that are most evident are called 

 the dominant, as distinct from the recessive, which are the less 

 evident. Quite aside from mere visibility, too, certain characters 

 seem more likely to appear in crossed forms than do their cor- 

 responding but equally noticeable characters (see the discus- 

 sion under Mendel's law and the illustrations of guinea pigs 

 in Chapter XI). 



Correlation of characters.^ The relations between tlie man)- 

 unit characters that make up any race are in many respects 

 striking. Certain characters move together in the relation of 

 cause and effect. Such characters are said to be highly corre- 

 lated. Certain others seem naturally opposed, and here the 

 1 " Principles of Breeding," chap. xiii. 



