PEAS AND BEANS 139 



membered that this plant offers exceptional 

 opportunities also for development by hybrid- 

 ization. In particular it should be recalled that 

 the extraordinary experiments through which 

 the Austrian monk, Mendel, made the discov- 

 eries that have created such commotion in the 

 biological world, were made with the common 

 garden pea. 



Reference to these experiments has been made 

 more than once, but it will be worth while to 

 examine them a little more in detail in the pres- 

 ent connection. 



The discovery that Mendel first made, to 

 which we have already referred, was that certain 

 qualities of the pea are grouped into very con- 

 spicuous pairs. 



His investigation led him to believe that there 

 are at least seven differentiating characters that 

 could be relied upon to reproduce themselves 

 with certainty in the offspring of the pea. These 

 characters, which he came to speak of as "unit" 

 characters, are the following: 



(1) The form of the ripe seed, which 

 may be roundish, either with or without 

 shallow wrinkles, or angular and deeply 

 wrinkled. 



(2) The color of the reserve material in the 

 cotyledons or little leaves that first appear when 



