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THE AMERICAN NATURALIST [Vol. XLIX 



primary mutation from f. typica, and twice as a secondary 

 mutation from mut. debilis. Although mut. debilis seems 

 to be an extreme recessive, derived from f. typica either 

 by the simultaneous or by the successive loss of two 

 factors for height, it throws mut. bilonga, which shows 

 a return to the stature of mut. semialta. In fact, mut. 

 bilonga would be identical with mut. semialta if it were 

 not for the difference in the length of the fruits. It has 

 already been stated that in both mut. semialta and mut. 

 debilis the fruits are by no means as reduced in size as 

 the foliage and stems. It seems almost as though the 



process of mutation, which results in the formation of 

 either of these dwarfs, does not involve the factors deter- 

 mining fruit size. In other words, the slight reduction in 

 size seems not to be due to a modification of the hereditary 

 qualities of the plant, but rather to diminished nutrition. 

 If this explanation is the true one, the fruits of mut. 



