1918] LANGDON—RAY SYSTEM OF QUERCUS 315 
of each of these trees. Likewise, from each tree twigs of unusual 
vigor of growth and shoots suppressed in their growth were pro- 
cured. For convenience the trees were numbered I, II, and III. 
Trees I and III are of about the same age, 55-60 years old, but 
tree I is larger and of slightly more vigorous growth than III. 
Tree II is younger than either I or III, about 35-40 years old. 
In the preparation of the wood for sectioning the process taken 
from CHAMBERLAIN’S Methods in Plant Histology was followed with 
slight modifications. The specimens of wood gathered from the 
different regions of these three trees were cut into small blocks and 
treated with hydrofluoric acid. After treating with the acid, wood 
should be left in equal parts glycerine and 30 per cent alcohol for 
several days or even weeks before sectioning to prevent the cortex 
of the stem from separating from the xylem. 
A series of transverse and tangential sections, both nodal and 
internodal, was made of twigs of all ages from 1 to 19 years, taken 
from the lower, center, and top portions of all three trees. This 
afforded an opportunity to compare woods of the same age and vigor 
of growth from different parts of the same tree and also from 
different trees, thus to ascertain whether certain ecological condi- 
tions, such as age of trees and vigorous or suppressed conditions of 
growth, may not tend toward the modification of the ray system of 
Quercus. 
Observations 
THE FIRST ANNUAL RING.—Although the uniseriate ray is the 
predominating type in the first formed secondary xylem of Quercus 
alba, multiseriate rays 2-6 cells in width also occur, radiating in 
pairs from the 5 lobes of the pith (fig. 1). Since these lobes or deep 
extensions of the pith into the surrounding woody tissue mark the 
region of leaf gaps, the initiation of pairs of wide rays at these 
particular points clearly indicates the relation of these rays to the 
two lateral leaf traces passing out at alternating nodes. Both the 
Wide and the linear rays extend radially from the pith through 
the phloem to the band of sclerenchyma separating the phloem and 
cortex regions of the stem. The effect of vigorous growth upon 
the general structure of the stem, and especially upon the ray system, 
is particularly noticeable in the first annual ring. Not only are 
