242 AGRICULTURE 



in the first generation, is called a " recessive ' 

 character ; whereas the character which was 

 exclusively present in the first generation, 

 and which was also displayed by 75 per cent, 

 of the individuals in the second generation, 

 is called the " dominant ' character. The 

 general law may be expressed by means of 

 such a diagram as is here inserted, where D 

 stands for a dominant character, and R for a 

 recessive. Plants possessing the recessive 

 character, if self-fertilized, all breed true, 

 whereas of the plants in the second generation 

 that possess the dominant character only 

 one-third breed true, two-thirds breaking 

 up in the proportion of three dominants to 

 one recessive. 



D R 



I I 



D (impure) 



i i ~r ~i 



D (pure) D (impure) D (impure) R (pure) 



D (pure) D (impure) D (impure) R (pure) 



It may be asked : If in the second generation 

 we get pure recessives and a certain proportion 

 of pure dominants, what is the advantage of 

 crossing as compared with sticking to the 



