ELISHA MITCHELL SCIENTIFIC JOURNAL 



determine how man} forms of offspring - hybrids would pro- 

 duce, to arrange these forms according- to their separate gen- 

 erations, and to ascertain their statistical relations to each 

 other. He found that the genus Pisum fulfilled the conditions 

 essential in the experimental plants. In the work which 

 extended over eight years the pea hybrids were found to be 

 not intermediate between the parental forms as regards the 

 two differentiating characters which were crossed, but one of 

 these characters was transmitted unchanged — the "domi- 

 nant" character of the pair, and the other seemed hardly to 

 be transmitted at all — the "recessive" character. When a 

 plant having a particular dominant character, as round, 

 smootish seeds, was crossed with one having a corresponding 

 character, namely, angular and deeply wrinkled seeds, the 

 resulting hybrid's seeds were all of them either round and 

 smootish or angular and wrinkled in the proportion of three 

 to one respectively. The next generation from the angular 

 seeds — bred true; from the round seeds | dominant), produced 

 all round seeds, which, however, subsequent generations 

 showed to be of two kinds — pure dominants breeding true, 

 and hybrids ( twice as many as the dominants) yielding pre- 

 cisely the same results as were observed in the first genera- 

 tion of the hybrid. 



The results may be exhibited graphically in the following 

 scheme, where D stands for a dominant character and R for a 

 recessive : 



D ^ R 



3 D 



1 R 



Hvbrid Seeds. 



1 D 



2DR 



R 



1st Generation. 



D D 2DR R 



R 2nd Generation. 



