Vererbung, Variation, Mutation. 255 



Breadth of seeds was noted in the crosses of Missouri dent with Cali- 

 fornia pop and with Tom Thumb. In both cases F^ was distinctly intermediate 

 betM^een the parents in breadth of seeds. The variability of the F^ lots was not 

 noticeably greater than that of the parents. The Fg generation, on the contrary, 

 showed a markedly greater variability than Fj, or the parents. 



Four different crosses were employed in the studies of the inheritance of 

 height of plant s. A peculiarity of these crosses is that in three of them the 

 Fj plants were almost as tall as the tall parent and in the fourth were conside- 

 rably taller than the mean of the two parents. Practically all of the F2 frater- 

 nities overlapped in height the inner extremes of their parents. Most of them 

 had a ränge of from near the mean height of one parent to the mean height of 

 the other parent and in one cross the F^ ränge was from the minus extreme of 

 the tall parent. The F3 families were very diverse in height and in variability. 



In some of the crosses, the height of plants was separated into its com- 

 ponents-number of nodes and internode length. In number of nodes the F^ fa- 

 milies were strictly intermediate between the parent varieties and the mean 

 number of nodes in F2 was practically the same as in F^, both of which facts 

 indicate that number of nodes is not appreciably affected by heterozygosis. As 

 in all the other quantitative characters studied, the Fg generation exhibited a 

 wide ränge of Variation and the several Fg families had very different mean 

 numbers of nodes, including types approaching those of the parents and also 

 various intermediate types. 



A study of internode lengths explains the excess in height of F^ plants 

 over the average of the parent heights. The number of nodes in F^ is appa- 

 rently always distinctly intermediate between the parent numbers, the internode 

 length is so greatly increased by heterozygosis that F^ plants are often nearly 

 as tall as the tall parent, and always taller than the average of the parent 

 heights — the former when the tall and short parents differ little and the latter 

 when they differ much in number of nodes. 



In two crosses, one parent of which produced numerous tillers and the 

 other few tillers, Fj^ was intermediate in number ofstalks per plant. In both 

 crosses Fg was more variable than F^ and in one cross the Fg ränge was from 

 one to eight stalks, w'hile five was the largest number observed in the parent 

 variety that tillered most freely. Among the F3 families, a few were practically 

 one-stalked types and a few others had a somewhat larger mean number of 

 stalks than the tillering parent and a ränge of Variation so great as to suggest 

 the possibility of isolating by selection a type with a still larger number of stalks. 



In earlinessF^ plants were intermediate between their parents. The Fg 

 generation more than filled in the gap between the parents in all cases where 

 exact records were mado and in one case had a ränge from below the mean of 

 the early parent to above the mean of the late parent. Very distinct types were 

 obtained in Fg, some of which were practically as eärly in flowering as the early 

 parent, but none of which where quite so late as the late-flowering parent. In 

 general the same relative order was maintained in ripening as in flowering. 



Pearl (Orono). 



805) Garrison, A. J., The Dominance of Recessives. In: Amer. Breeders 

 Mag., Vol. IV, Nr. 1, S. 34—38, 1913. 



The author experimented in crossing American plums and also hybridizing 

 with Japans with a view of testing the principles of supremacy of color, indivi- 

 dual potency, and natural selection by surrounding the seedlings with uniformily 



