Inherilancc in the Higher Plants 



87 



seed, that seed breeds true to the character starchiness. 

 When two gametes both lacking the factor starchiness 

 {s) produce a seed, that seed breeds true to the character 

 non-starchiness or sweetness. The production of gametes 

 and zygotes may be illustrated thus: 



Starchy zygote Non-starchy zygote 



Male 

 gametes 



|S|S| 



s] [s 



\/ 



Islsl 



Female 

 gametes 



Male 

 gametes 



S S 



S S 



S S 



Female 

 gametes 



Starchy 

 zygote 



Non-starchy 

 zygote 



When a gamete from a starchy strain fuses with a gamete 

 from a non-starchy strain a hybrid zygote is formed. This 

 zygote is starchy like the starchy parent because the 

 presence of the starchy factor from one parent is suflficient 

 to cause the development of starch. But the gametes, both 

 male and female, formed by this hybrid or heterozygote, are 

 not alike. Half of them contain the starchy factor and 

 half of them are without it. This being true, when the male 

 and female gametes of the hybrid pair indiscriminately, the 

 following combinations occur in equal numbers : 



Ss 



sS 



ss 



The first term of this ratio, resulting from the fusion of 

 two starchy gametes, is a starchy zygote that breeds true; 

 the second and third terms, resulting from the fusion of a 

 starchy and a non-starchy gamete, are again hybrid in 



