GALLS PRODUCED BY TWO CEDAR RUST FUNGI 
251 
its entire length. A layer of cork has been laid down in the cortical tissue as denoted 
by the dark line extending from the base to about the center of the leaf (see a-b 
in photograph). 
Plate XVI 
Figs, i and 2. Sections of leaves (/) affected with G. globosum showing 
resin ducts {r) and their relation to the stertis. The white area beneath the epidermis 
{k) in both galls is the corky covering which develops very early in galls caused by this 
fungus. 
Fig. 3. Section of a gall in a more advanced stage than represented in Figs, i 
and 2. The tip of the leaf is evident at / and the corky layer {K) surrounds the gall 
on all free sides. The gall is firmly attached to the stem and it can easily be seen 
how the condition shown in PI. XV, Fig. 5, develops. 
