ENDOTHIA CANKER OF CHESTNUT 557 
trees as to the American ones. Not a single tree could be found which 
had been killed entirely by this disease, although there might have been 
such trees which had been removed by the ever active and economic 
Chinese farmers. Dead limbs, however, were often seen and many a 
saw wound showed where limbs had been removed. . . . The wounds 
on the bigger majority of the trees were in the process of healing.” 
Shear and Stevens (1913 b) made cultures from the Chinese specimens 
and found that all the cultural characters are identical with those of 
Endothia parasitica. Spore measurements agreed very closely, and 
inoculations made on native American chestnuts produced typical cankers. 
The writers of this bulletin have grown the Chinese fungus in culture 
and cannot distinguish it from the American chestnut-canker fungus. 
It may now be regarded as practically certain that the early home of 
Endothia parasitica was the Orient. 
Morphology 
Stromata 
Cankers of a season’s growth or older show numerous orange-colored 
or reddish-brown, erumpent and projecting, stromata (Plate XX XVII). 
On smooth bark the stromata are usually elongated horizontally 
and average about 2.4 by 1.2 millimeters, by 1.3 millimeter in 
depth. The part beneath the ruptured cork layer is flattened out on the 
collenchyma and is broader than the exposed part (Figs. 84 and 8s). 
The stromata, however, vary widely in size with environment and season; 
they become much larger in moist situations than in dry surroundings 
where they are exposed to desiccation. On-old, rough bark they do not 
occur singly, as shown in Plate XX XVII, but are found only in the 
crevices of the bark, often united in solid lines several inches long so that 
they apparently form one long stroma. 
The color varies with age, being sulfur yellow at first, later becoming 
orange, reddish-brown, and finally cinnamon-brown on the surface, 
but always lighter-colored on the inside. When in a shaded:and moist 
location — as, for example, on the underside of a log — the stromata 
remain light yellow. 
In the fresh condition the stromata are soft, dry, subcoriaceous, easily 
torn apart, and of rather lodse, indefinite outline. A cross section shows 
that the center of the stroma is composed of a comparatively loose tangle 
of branched and septate hyphe, containing yellow pigment. Throughout 
the basal parts are scattered stone cells, bast fibers, and remnants of the 
walls of collenchyma cells. The entire exposed surface of the stroma is 
covered by a rind layer, in which the hyphal cells are shorter and thicker, 
almost or quite isodiametric, and with heavier walls than in the interior. 
