1918] FLINT—STRUCTURE OF WOOD 559 
uniseriate rays as are the broad rays in Quercus. Because of this 
sharp contrast, and because of the similar origin of the broad 
rays, they are obviously the exact counterparts of the broad 
parenchymatous bands in the secondary wood of Quercus. 
In conclusion, I wish to thank Dr. E. C. Jerrrey of this labor- 
atory for material and advice rendered during the course of this 
investigation. 
. 
HARVARD UNIVERSITY 
CAMBRIDGE, Mass. 
EXPLANATION OF PLATES x XI 
Fic. 1.—Longitudinal tangential section, aggregate ray of seedling of 
Quercus velutina; X 100. 
Fic. 2.—Transverse section, wood of seedling of Q. velutina; Xt00. 
Fic. 3.—Longitudinal tangential section, wood of Q. velutina; X 200. 
Fic. 4.—Transverse section, wood of stem of Vaccinium corymbosum; 
Fic. 5.—Transverse section, wood of stem of V. corymbosum; XX 200. 
Fic. 6.—Longitudinal tangential section, wood of stem of V. corymbosum; 
X 100. 
—Longitudinal tangential section, wood of subterranean stem of 
vs pemnolonicam; 100. 
Fi —Longitudinal tangential section, wood of root of V. pennsyloani- 
cum; pes lon 
1G. 9.—Longitudinal tangential section, wood of root of Gaylussacia 
species; 100, 
Fic. ro.—Longitudinal tangential section, wood of root of Rhododendron 
species; XX 100. 
Fic. 11.—Transverse section, wood of root of Rhododendron species; 
X 200. . 
Fic. 12.—Longitudinal tangential section, wood of stem of Arbutus 
species; 100 
by 
x 
