134 Adkinson . — Some Features of the Anatomy of the Vitaceae. 
ing of enlarged rays originally connected with the leaf-trace. Hence, for 
Quercus at least, broad rays are secondary and uniseriate rays are primitive. 
Finally, Eames has explained the development of the herbaceous stem in the 
Dicotyledons by the localization of protoxylem and ray parenchyma with 
the reduction of lignified tissue and the more or less complete disappearance 
of the interfascicular cambium. Within the bundles, the uniseriate ray 
either disappears completely or is changed into a radial sheet of wood 
parenchyma, still appearing like a ray in cross-section, but elongate in the 
direction of the vertical axis of the stem. 
In view of this latter explanation of the origin of the herbaceous stem, 
the wood structure of Vitis and other Vitaceae was re-examined for evidence 
upon the primitive condition, the mode of development, and the relation of 
the vine habit to the herbaceous type of Dicotyledon. 
As described in detail by Strasburger , 1 the wood of Vitis Labrusca , L., 
consists of wood fibres, septate fibres, tracheides, vessels, and wood 
parenchyma cells. The wood parenchyma is distributed mainly about the 
vessels adjacent to the radial rows of tracheal elements, and beside the rays. 
It is sometimes scattered in radial rows through the wood. 
Of chief interest in this study are the multiseriate rays, the so-called 
s primary rays ’ of older text-books, which extend as plates of parenchyma 
seven to ten cells wide, continuously for a long distance vertically through 
the stem, although they are interrupted at intervals by the crossing over of 
tracheides, and less frequently of vessels. The ray cells elongate radially, 
are rectangular in cross and radial section, and in tangential section five or six 
angled. The peripheral cells along the sides vary in shape according to their 
location, and often are elongate in the vertical direction. Thus a sharp dis- 
tinction between the ray cells and adjacent wood parenchyma cannot always 
be established. The rays extend from pith to cortex. Between the primary 
wood bundles, the ray cells are continuous with the round, narrow-lumened, 
thick-walled, vertically elongate, amyliferous cells which form a sheath be- 
tween the protoxylem and the broad, thin-walled cells of the pith. By 
gradual transition these elongate cells give place to the rectangular ray 
cells which become more and more elongate radially. The rays grow 
wider towards the cortex by the addition of adjacent fibres which gradually 
in the same row assume the characteristics of typical ray cells. 
These multiseriate rays occur in the stem of the eleven species of Vitis 
examined. Specific differences exist in the width of the ray, the frequency 
of the tracheid bridges, and the number of fibres transformed into ray cells. 
The question now arises as to the origin of the multiseriate ray. Is it 
a primitive condition in Vitis, or has it developed secondarily, as in 
Qnercus ? 
1 Strasburger, E. : Histologische Beitrage, III. Ueber den Bau und die Verrichtungen der 
Leitungsbahnen in den Pflanzen, Jena, 1891, p. 239. 
