238 



Inheritance in Sweet Peas and Stocks. 



in both purples and reds. Several of these are merely superposed on the 

 primary classes, while others are more complex and require further analysis. 

 The distribution of the colours shows further complications when some 

 coloured strains were introduced as original parents. 



" Eeversion " is thus seen to be a simple and orderly phenomenon, due 

 to the meeting of factors belonging to distinct though complementary allelo- 

 morphic pairs, which at some moment in the phylogeny of the varieties have 

 each lost their complement. 



Pollen-characters in Sweet Peas. — Gametic coupling of a novel kind exists 

 in this case. The whole generation in F2 consists of 3 long : 1 round. 

 The whites taken alone also are 3 long : 1 round. But in the purples there 

 is a great deficiency of rounds, while in the reds they are greatly in excess. 

 This result indicates that there is a partial coupling of the long pollen- 

 character with the factor B, and a corresponding coupling of round pollen 

 with b. This peculiarity only occurs in families which contain both 

 purple and red members. The gametic output of F x in these cases is 

 approximately 



7AB + lA& + laB + 7a&, 

 where A is long, and a round pollen. This arrangement gives a close 

 approach to the observed figures : — 



Purple. Bed. White. 



t ' 1 t * 1 t * \ 



Long. Kound. Long. Bound. Long. Bound. 



Observed 1528 106 117 381 1199 394 



Calculated 1448-5 1227 1227 401-5 1220-5 407*4 



