226 HEREDITY AND ENVIRONMENT 



the different varieties are distinguished by 

 constant differentiating characters. Mendel 

 devoted his attention to seven of these charac- 

 ters, which he followed through several gener- 

 ations of hybrids, viz., 



(1) Differences in the form of the ripe 

 seeds, whether round or wrinkled. 



(2) Differences in the color of the food 

 material within the seeds, whether pale yel- 

 low, orange or green. 



(3) Differences in the color of the seed 

 coats (and in some cases of the flowers also) , 

 whether white, gray, gray brown, leather 

 brown, with or without violet spots. 



(4) Differences in the form of the ripe 

 pods, whether simply inflated or constricted 

 between the seeds. 



(5) Differences in the color of the unripe 

 pods, whether light to dark green, or vividly 

 yellow. 



(6) Differences in the positions of the 

 flowers, whether axial, that is distributed 

 along the stem, or terminal, that is bunched 

 at the top of the stem. 



