32 Nebraska Agricultural Exp. Station, Research Bui. 12 
lightly stained while the adjoining cells always took on a deep 
stain. By employing this stain it was found that unstained or 
lightly stained spots appeared in sections made beyond the 
actual discoloration in the branches and that these spots cor- 
responded in position with the area occupied by the fungus in 
infected sections. 
The cells in such spots did not respond when treated suc- 
cessively with 20 per cent cane sugar and distilled water. 
However, the surrounding cells did not always respond sat- 
isfactorily but there was sufficient response to show the pres- 
ence of living protoplasm in the majority of cases. 
It was noted that in general the mycelium grows more 
rapidly in a downward than in an upward direction. This is 
especially true in inoculations on the smaller limbs, and on 
the larger limbs where a great deal of growth has been made. 
In the larger limbs where the hyphae have proceeded only a 
short distance the average growth is as great in one direction 
as another. The difference in growth in smaller limbs is per- 
haps due to the fact that the ascending hyphae are constantly 
encountering younger wood while the descending hyphae en- 
counter older wood. This theory is upheld by the fact that in 
the roots the greatest growth is toward the trunk. 
INOCULATIONS IN STUBS 
In the stub inoculations (those which were made by cutting 
off a branch 10 to 12 inches above its base and placing the in- 
oculum over the entire cut surface), the relative amount of 
growth in tissues of different ages as indicated in table 6 cor- 
responds very closely with the data given in table 5. In stub 
inoculations, however, the growth is much more rapid owing 
to the death of the tissues, caused by removing the foliage. 
Almost as rapid growth was secured by keeping the foliage 
removed from branches which had been inoculated. In table 
6 the number of rings of annual growth free from infection is 
given. This shows the radial distribution of the mycelium 5 
and 10 inches from the point of inoculation. It was impossi- 
ble to show the longitudinal distribution owing to the fact that 
the mycelium had entered the trunk of the trees. 
Very few conspicuous cankers were produced by inocula- 
tions where the limbs were not injured in some way. In the 
stub inoculations, the first infection usually occurred close to 
the center of the wound and the mycelium proceeded rapidly 
toward the trunk. The newer wood and finally the bark was 
invaded beginning at the end of the stub and extending toward 
