Oct., 1913-Mar., 1914 
Illustrations 
XI 
Plate 
Page 
LIV. Cross section of cow oak, a white oak, showing normal and 
abnormal tyloses. Fig. 1.—Wound tyloses induced by 
the felling of the tree and the sudden cessation of sap 
flow. Fig. 2.—No tyloses; empty vessels. Fig. 3.— 
Young and well-developed normal tyloses. 470 
LV. Fig. 1.—Cross section of a diffuse porous wood, yellow pop¬ 
lar or tulip, showing scattered tyloses. Fig. 2.—Cross 
section of a ring porous wood, osage orange, with vasi- 
centric parenchyma, showing abundantly developed 
tyloses. 470 
I/VI. Fig. i.~Cross section of western white pine, showing ray 
tyloses, closed vertical resin canal in young sap wood, and 
nuclei visible in epithelial cells of canal which is begin¬ 
ning to split open. Fig. 2.—Tangential section of Nor¬ 
way pine, showing ray tyloses. 470 
I/VTI. Fig. 1.—Cross section view of shortleaf pine, showing open 
and partly closed vertical resin canals. Fig. 2.—Heart- 
wood of Sitka spruce, showing closed vertical canal. 470 
I/VIII. Open and closed horizontal canals in sapwood. Fig. 1.— 
Open canal in tamarack. Fig. 2.—Partly closed canal 
with distended epithelial cells in Douglas fir. Fig. 3.— 
Young canal which has never opened in western white 
pine. Fig. 4.—Open canal in red spruce surrounded by 
thick-walled epithelium. Fig. 5.—Partly closed canal 
in red spruce. Fig. 6.—Closed canal in Engelmann 
spruce. 470 
LIX. Fig. 1.—hog from collection of woods in the Forest-Products 
Laboratory—a specimen of the material used in this study. 
Fig. 2.—Specimens of woods showing creosote penetrance 
in sapwood and heartwood as affected by tyloses. Speci¬ 
men A.—Red oak. Specimen B.—White oak. Specimen 
C.—Pignut hickory. 470 
LX. Fig. 1.—River birch with bark removed, showing larval 
mines of Agromyza pruinosa. Fig. 2.—Section through 
wood of river birch, showing “ pith-ray flecks'* produced 
by the work of Agromyza pruinosa . 474 
LXI. Fig. 1.— Agromyza pruinosa: Larva and details. Fig. 2.— 
Agromyza pruinosa: Pupa. Fig. 3.— Agromyza pruinosa: 
Adult male. Fig. 4.— Agromyza pruinosa: Abdomen of 
adult female, showing ovipositor. Fig. 5.— Sympha agro- 
myzae: Adult. 474 
LXII. Fig. 1.—Wheat seedlings from seed inoculated with spores 
of Helminihosporium gramineum and from seed exter¬ 
nally sterilized. Fig. 2.—Barley seedlings from seed 
inoculated with Helminihosporium gramineum and from 
sterilized seed. Fig. 3.—Wheat seedlings from seed in¬ 
oculated with spores of Fusarium culmorum from oat 
seedlings and from seed externally sterilized. Fig. 4.— 
Barley seedlings from seed inoculated with spores of 
Fusarium culmorum from oat seedlings and from seed 
externally sterilized. Fig. 5.—Oat seedlings from seed 
inoculated with spores of Fusarium culmorum from oat 
seedlings and from seed externally sterilized 
490 
