1918] FLINT—STRUCTURE OF WOOD 557 
ing points of similarity with the conditions already mentioned. 
V. corymbosum, as shown in transverse view by fig. 4, is seen to have 
broad and also uniseriate rays, as does Quercus. Although the 
large rays are not so broad as the corresponding rays of the oak, 
yet they are similar to the latter in the strong contrast which they 
present to the small uniseriate ones. The large ray of V. corym- 
bosum (fig. 4) is composed of two kinds of cells: light, rather 
larger ones; and dark, smaller ones (the ordinary parenchymatous 
ray cells), a condition which exactly parallels the organization of 
the ray of the oak just noted. Fig. 5 shows a portion of this same 
transverse view of the wood of the stem of V. corymbosum more 
highly magnified, so that the twofold composition of the ray becomes 
even more apparent. Fig. 6is a tangential aspect of the wood of the 
stem of V. corymbosum corresponding to fig. 4. In this plane also 
the two kinds of rays, uniseriate and broad, are likewise visible. 
The presence of two kinds of cells in the large ray, one dark and 
‘rather small, the other light and somewhat larger, can also be dis- 
tinguished clearly. Obviously the large ray is a compound struc- 
ture, just as has been proved in the case of the corresponding large 
rays of the oak, with which the large ray of V. corymbosum appears 
to be identical in so far as it is composed of the two kinds of cells 
described. 
Vaccinium pennsylvanicum shows the same situation as V. corym- 
bosum, as is vouched for by figs. 7 and 8. In fig. 7 the contrast 
between broad and narrow rays is readily distinguished. The large 
number of light colored cells present in the broad ray plainly shows 
indication of origin from the transformation of fibrous elements into 
parenchyma. An enlarged view of this situation is given in fig. 8, 
which represents a higher magnification. The light cells are 
strikingly different from the ordinary ray cells which they accom- 
pany, and the seriate ones in the central portion are obviously 
derived from a transformed fiber. The whole structure is con- 
sequently a compound ray resembling that found in the wood 
of the oak. In fig. 9 the same condition is noted as in fig. 7, 
namely, rays of two sharply contrasting types, broad and uniseriate. 
Of these the large ones are compound in structure, showing deriva- 
tion by the fusion of small rays as well as by the transformation 
