i8o MENDELISM 



appeared. The characters dealt with by Mendel were 

 as follows, the dominant member of the pair being in 

 each case placed first : 



Smooth seeds, and wrinkled seeds. 



Yellow, and green reserve material i.e., cotyledons. 



Deeply coloured (grey), and nearly colourless testas 

 or seed-coats. 



Inflated or stiff, and wrinkled or soft pods. 



Green, and yellow pods. 



Flowers scattered up the stem, and flowers in a 

 terminal bunch or umbel. 



Tall, and dwarf stems. 



As the result of these experiments Mendel came to 

 the conclusion with which his name is now closely 

 associated that the male and female germ-cells of 

 hybrid plants contain each of them one or the other 

 member only of any pair of differentiating characters 

 exhibited by the parents, and that each member of 

 such a pair of characters is represented in an equal 

 number of germ-cells of both sexes. Furthermore, 

 separate pairs of differentiating characters (allelo- 

 morphs) conform to this law in complete independence 

 of one another. 



Although in Mendel's own experiments one member 

 of each pair of differentiating characters was always 

 dominant, dominance is by no means an universal 

 phenomenon when different varieties of plants are 

 crossed together. In a considerable number of in- 

 stances the heterozygote is found to exhibit an appear- 

 ance which is more or less intermediate between the 

 types of character shown by the parents. It may be 



