Hybridization of Vitis Rotundifolia 
13 
rangements of the cork cambium. The quantity varies from that shown 
in Figure 51 to that of Figure 58, and its position in relation to other 
tissues varies greatly in depth as shown in Figures 52 and 63. In 
Fi gures 68-74 inclusive, the drying out of the cells outside of the suber- 
ized layer was so complete that this portion of the cortex fell off either 
before or after cutting the section. In each of these cases, the phellogen 
was located inside of the sclerenchyma bundles. 
HYBRIDS VAR. WINCHELL—V. ROTUNDIFOLIA HYBRID X V. 
ROTU NDI FOLIA 
There is only one vine of this cross and it is so small and weak 
that it would be unwise to draw any conclusions from it. It is, how¬ 
ever, predominantly V. rotundifolia in character, which, inasmuch as 
this is the staminate parent, would indicate its hybrid character. The 
stem and hark resemble this parent and the pith is small, light green 
and continuous. The transverse section of the stem shows strongly the 
T . rotundifolia parentage in the pattern of the phloem bundle, the 
proportion of elements and the presence of lenticels. At one point of 
this section there is an excessive amount of dry cortex outside of the 
phelloderm resembling the hybrids of the Fi generation. 
DISCUSSION 
It has been possible in the hybridization of Vitis species to cross 
individuals that have considerable difference in the anatomy of the 
stem structure. These characters are inherited by the hybrid offspring 
so that there is an opportunity to study the inheritance of characters 
that are of greater fundamental importance from a genetical viewpoint 
than such superficial ones as color, weight, size, etc. Ho doubt, some 
of these characters may be correlated with other external morpho¬ 
logical ones, but the study of the inheritance of these essential struc¬ 
tural characters should be of great value to an understanding of the 
principles of heredity. 
The varying degree of expression of the blended intermediate char¬ 
acter in the offspring would probably be best explained by a multiple 
factor hypothesis. The small number of individuals available and the 
fact that only the generation has been studied would make it im¬ 
possible to draw any definite conclusions. 
It is very significant, however, that the intermediate condition of 
the anatomical stem characters varies in degree not only in the differ¬ 
ent hybrid vines, but also in the same individual. It is a striking fact 
that neighboring and even adjacent bundles in the same transverse sec¬ 
tion may resemble different parents. In such small stems, this con¬ 
dition cannot be explained as a response to external environmental 
factors. This condition approaches a chimera but differs from it in 
the lack of total dominance of expression of either parent. Actually 
there are different degrees of blending in the same individual. There 
