TAKE WO HE.MMI * 0 g 
In 1914, Keefer 13) reported his microchemical and histological studies 
of the effect of the fungus {Endothia parasitica) on the bark and the wood of 
the chestnut canker. I tried the same studies on our cherry canker, but the 
results were not so conspicuous as in the case of the chestnut tree, chiefly 
owing to the disturbance caused by the destruction of the cell-walls by the 
fungus and the formation of the gum. But I got, on the whole, the following 
results : — 
The primary cortex. The cork cells are practically unaffected by the 
fungus, with the exception of the rupture which is apparently produced by 
mechanical pressure from below. No hyphae were seen penetrating the cell 
walls or passing between them. Perhaps the only change to be observed was 
with respect to the arrangement of the tissue. At points where the stromata 
are forming beneath the periderm, there is a bulging of the layer, followed 
by a complete rupture during the maturation of the perithecia. 
The sclerenchyma, which have highly lignified walls enclosing a very 
narrow empty cell lumen, are also not affected by the fungus, — the structure, 
size, arrangement, and chemical nature being unchanged. 
The collenchyma and the thin walled parenchyma composed of cells 
having more or less pure cellulose membrane, are destroyed by the fungus, 
and the mycelium is penetrating and ramifying throughout those tissues. 
As Keefer has shown, I have also found that the cellulose cell walls become 
partially lignified. The degree of lignificatiori, however, is very poor in my 
case. Such lignified cells are only sparingly found by a microchemical test. 
As to the change in the cell contents, I could not get clear results, but it is 
apparent, according to the test, that the tannin is increased more or less in 
tin >se cells. 
The bast zone. This is chiefly composed of sclerenchyma in the form 
cf bast fibers and sieve tubes, as well as of phloem parenchyma and medullary 
rays. The sieve tubes and the parenchyma, which have more or less pure 
cellulose cell-walls, are easily destroyed by the fungus. Those cells are so 
strongly dissolved that their original shapes are lost, and the mycelium is 
