400 BOTANICAL GAZETTE [JUNE 
The affected portion of a stem was split in two and the two halves 
placed in a moist chamber. In one night a luxuriant Botrytis 
growth developed, being confined entirely to the cortex, most 
abundant in the worst affected portion and shading off gradually 
in the direction of what had been the upper part of the stem. 
Toward the boundary between the affected and unaffected areas 
no Botrytis appeared, but an abundant mycelium. In this por- 
tion, 2. ¢., the most newly affected, there appeared later ordinary 
black sclerotia having a long narrow form and located in the 
cortex, especially along the cut edges. The Botrytis gradually 
advanced, but was much more abundant back in the older part. 
Gelatine cultures were made with conidia and portions of the 
affected bark. The former produced a considerable mycelium, 
rather few conidia, and some sclerotia. The latter developed a 
similar mycelium,very few conidia, and numerous, larger, roundish 
sclerotia. Cultures were also made in the portions of the vege- 
tative mycelium which appeared in the moist chamber upon the 
most newly affected portion of the stem (where no Botrytis 
appeared). This gave a vigorous mycelium with sclerotia, but 
no Botrytis. All of the sclerotia obtained from this material 
showed the characteristics of those of the botrytis type of the 
lettuce disease, being thin and joined with the substratum. 
Several more affected trees were found in the nursery, both 
Tiha parvifolia and T. grandifolia. These showed the same symp- 
toms as before. Some that were most affected seemed to be 
quite dead, and in the lower part of the stem the bark was quite 
destroyed, the wood being laid bare, but covered more or less 
with shreds of the bast which still remained. A few ordinary 
black sclerotia were found, but most were of the half-formed 
variety, covered with Botrytis. These appeared to have devel- 
oped the previous fall, producing conidia in the spring. 
The main features of this disease are these: a vigorous 
mycelium, starting apparently at the surface of the ground, pro- 
ceeded upward through the cortical parenchyma, completely 
destroying it and eventually killing the plant. Sclerotia were 
developed upon the surface but reverted to the production © 
