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BOTANICAL GAZETTE 



that the color of the fruits and the thickness of the pedicels are 

 independent pairs of unit characters, and we may consider A . alba 

 as perhaps having originated from A . rubra through two mutations, 

 in one of which the chief change was in the color of the berry, 

 while in the other it was in the thickening of the pedicels. If there 

 are two Mendelian pairs here, however, it is difficult to see why 

 the two combination types, (i) white berries and thin pedicels and 

 (2) red berries and thick pedicels, are not of more frequent occur- 

 rence. Crossing experiments, if they could be carried out, would 

 doubtless throw light on the situation and would be of very great 

 interest. Red berries perhaps would be dominant over white 

 berries, but since a red tip remains to some at least of the white 

 berries, the white may be dominant and the plants with red-tipped 

 berries heterozygous. Whether there would be any dominance of 

 slender or thick pedicels is impossible to say. 



A more careful analysis, however, discloses other differences 

 besides those mentioned. Thus Lloyd 12 describes the differences 

 between the fruits of A . rubra and A . alba as follows : A . alba has its 

 fruit (1) on thickened pedicels, (2) smaller, (3) with a larger tip, 

 (4) with a much thicker "integument," (5) without pulp, (6) with 

 larger and fewer seeds (6 instead of about 12), whose sides are 

 more slanting and their surface smooth (not roughened). They 

 also cite observations of Mrs. Stowell, who found that in A. alba 

 the pedicels were much harder, firmer, and darker, and with much 

 larger starch grains." These authors cite the occasional occurrence 



