12 
Hybridization of Vitis Rotundifolia 
Wood. The wood is soft and very brittle, snapping off easily at the 
node and only a little less easily at the internode. 1 he section of the 
stem is almost round in outline. 
Pith. The diameter of the pith varies widely between that of the 
two parents, which are extremes in either direction for size of all the 
vines examined. In color, some have a light brown pith and others 
light green as in I . rotundifolia. In this latter case, the pith is usually 
continuous without a distinct diaphragm at the node. The others ha\ e 
a more or less complete diaphragm. Of the twenty-six examined, eleven 
have definite diaphragms at the node visible without the use of the lens. 
In those with continuous pith the cells at the node were compacted and 
lignified to a varying extent. 
Xylem. The xylem is more nearly like that of the variety Winchell, 
especially in the size and shape of cells, although the walls are thicker 
than those of this variety. 
Phloem. In these hybrids there is a great variation in the pattern 
of the phloem as examined in the transverse section. In eleven of the 
twenty-six the hard and soft hast are disposed in a manner smiilai to 
that in the Euvitis species. In the others, there is more or less simi¬ 
larity to the staminate parent, although there is a greater tendency for 
the hard bast to form tangential layers across the bundle regardless of 
the shape of the bundle than in the case of T T . vinifera hybrids. The 
bundle of sclerencliyma fibers varies with the type of phloem bundle. 
The square Winchell-like bundle is accompanied by a bundle of scle- 
renchyma fibers similar to the same species. 
The camera lucida diagrams shown in Figures 48-75 inclusive, repre¬ 
sent bundles from each of the hybrids of this cross ; Figures 5o and 56 
being from the same vine, and Figures 60 and 61 from another single 
vine. The range of the intermediate character of the hard bast is shown 
by Figures 49, 51, 53, 56, 60 and 66. This is also well shown in the one 
vine represented by Figures 55 and 56, or in Figure 62. The vines 
represented by Figures 55 and 58 are interesting because of the scarcity 
of hard hast present in the phloem. 
Rays. The rays show the same correlation with the shape of the 
phloem tissue as in the case of the V. vinifera hybrids, that is, the 
intervascular ray expands by cell multiplication when the phloem 
bundle is sufficiently triangular in shape to cause a tangential strain 
(Fig. 76). 
Cortex. The cortex of these hybrids is extremely irregular. The 
predominant character is the excessive amount of cork cambium at 
scattered points in the transverse section (Fig. 77). This lack of defi¬ 
nite character for the phellogen is greater than in the case of the V. 
vinifera hybrids. I 11 some instances, the entire thickness of the cortex 
seems to he completely of suberized tissue (Figs. 76 and 78). 
The diagrams in Figures 48-75 illustrate the various amounts and ar- 
