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ably most reasonable to assume that the mother plant is heterozy- 

 gous with regard to the factor for leaftime, and in that case, very early 

 leaftime must be dominant. Among the descendants of 877, there 

 were two individuals that differed much from the normal, a copper 

 beech {Fagus sylvatica atropurpurea) and a variegated beech, (Fagus 

 sylvatica, fol. argent, variegat.), which points to a very complicated 

 heterozygous condition in the mother plant. 



But it is scarcely likely that the matter is so simple as we 

 have assumed. The truth is probably rather that leaftime is, in 

 each individual case, conditioned by a complicated combination 

 of genotypic factors, which according to the circumstances, can 

 operate, at one time, in the same direction, and at another may 

 counteract each other. The experiments show that, with regard 

 to leaftime, there are, not only early and normal beeches, but also 

 a series that varies with regard to leaftime from very early to very 

 late. The leaftime of the descendants is, on the whole, parallel to 

 that of the parents, but exceptions occur. 



The most important point is that the experiments show that, 

 within Fagus sylvatica, there are sub-species, isoreag- 

 ents, that are different with regard to leaftime. 



