528 VARIATIONS 



excepting that father and mother factors for the same character 

 do not appear together. When the sperms and eggs pair and 

 fuse in fertilization, the associations of factors that result may be of 

 numerous kinds, for a sperm with any kind of an association of 

 factors may unite with an egg having the same or any other kind 

 of an association of factors. Consequently, offspring commonly 

 differ from each other as well as from their parents in their 

 combinations of characters. One child may have the mother's 

 nose and the father's disposition, while another child may have 

 the father's nose and the mother's disposition. Among plants, 

 one individual of a progeny may take after the mother plant in 

 size, color of flowers, shape of seeds, etc., and after the father 

 plant in shape of leaves, thickness of stalk, arrangement of 

 flowers, etc. ; while another individual of the same progeny may 

 have a very different combination of characters. Sometimes, 

 through the association of factors, the offspring may be inter- 

 mediate between parents, as in case of height, length of ears in 

 Corn, and so on. Characters not developed in the parents but 

 handed down from grandparents or more rernote ancestors often 

 develop in the offspring in combination with parental characters. 

 In some cases certain parental factors, when associated in the 

 offspring, produce something new, as red-flowered offspring from 

 white- flowered parents. Again certain characters depend upon 

 a number of factors and the amount of the character depends upon 

 the number of factors associated. For example, in some varieties 

 of Wheat the redness of the kernel depends upon three factors, 

 and redness varies with the number of factors associated, being 

 only slight when one factor is present and most intense when all 

 three factors are present. Thus, due to the numerous ways fac- 

 tors may be separated and associated in the reduction division 

 and combined in fertilization, numerous differences in the 

 offspring are accounted for. (Fig. 4?4-) In fact, plant breeders 

 often resort to crossing to produce variations or break the type as 

 commonly expressed. 



Since each individual plant or animal has many more factors 

 for characters than chromosomes, each chromosome must consist 

 of the factors for a number of characters. In each chromosome 

 there is an association of certain factors, and due to the associa- 

 tions of certain factors certain characters develop associated or 

 linked. Thus in mankind, maleness and beard are associated, 



