PLATE i 
The prints were made by bringing the leaves, from which the chlorophyll had been 
removed, in direct contact with Velox paper. 
A. —Black raspberry leaflet, dorsal side. One-half of the leaflet, except a small por¬ 
tion of the lower left, infected and bearing spermogonia. Stomata on the upper side 
only where hyphae are present. 
B. —Leaf of black raspberry, ventral surface. Left half of terminal leaflet infected; 
hyphae are beginning to invade the right half. Most of the left basal leaflet is infected; 
dark area along the midrib devoid of hyphae. No stomata were found on the dorsal 
side of the right basal leaflet, which was not infected, and none on the upper side of 
the others except where infected. 
C. —Black raspberry, ventral surface. At the left the boundary line between in¬ 
fected and uninfected areas is very clear cut, being limited by a large lateral vein. 
On the right side the mycelium is advancing from the margin into the regions be¬ 
tween the second and third veins; stomata present on the dorsal side only where leaf 
is infected. 
D and E.—Leaflets from the same plant one month later; that is, one month after 
sowing aecidiospores of the Gymnoconia on the upper side of these leaves. Dorsal 
stomata and teleutosori only on areas now bearing aecidia. Teleutosori also on ventral 
side among aecidia. 
F.—Leaf of Kittatinny blackberry aecidia maturing. About the same number of 
stomata were found on both sides of the portions of the leaflets bearing aecidia. No 
stomata on dorsal side of basal leaflet at the right. 
G.—Larger leaflet of Kittatinny blackberry, showing that the fungus advances from 
the margin toward the midrib. Dorsal stomata only on the area where aecidia are 
present on the ventral side. No spermogonia were formed. 
o 
