3. THE WHITE SECRETION.--The most striking peculiarity of the callus tissue, is its abundant content of a thickish, milky, white substance. This came to light immediately when I cut into the callus, and it showed up very clearly when I shaved off the outer layers of dead cork tissue. The white material is not evenly distributed through the irregular grain of the wound tissue, but is particularly abundant in small spots or pockets which are especially conspicuous in the callused margin of the lesion. Soon after exposure to the air the cut bark, and particularly the white substance, redden rapidly, indicating oxidation. This peculiarity is of course true of all chestnut bark, yet here the reddening seems to be deeper and more rapid than the normal. No chemical analysis has yet been made of this substance, but there is sufficient other evidence at hand to warrant a tentative statement that it is very rich in tannin or tannin compounds, and that possibly the quality of resistance is bound up with the nature of this material. 4. THE STRIP CONDITION.--Some of the trees showed the living bark restricted to a narrow, flattened, rope-like strip running up the trunk to one or a very few branches (Plate 1, Fig. 3). In these cases all of the bark was of the callus nature, rich in the resistant substance, and plentifully besprinkled with small Endothia lesions, while underneath were a number of layers of functioning wood. The rest of the trunk was bare, weathered gray, with traces on its surface of old cankers, and evidently dead for a long period. This type of tree was so commonly found that I have called it the strip tree. INOCULATIONS The very fact that these trees are now alive in this New York region is pretty good proof of their resistance. But of course the most conclusive test is by inoculation with the fungus in question. If the fungus grows slowly in these trees as compared with its growth on non-resistant stock, then no one can deny that they are resistant. I will not bore you with figures of tables, I will only give you the results. The average growth of the fungus in 289 inoculations on the resistant trees was about 1/3 as fast as on non-resistant stock, and taking the rate of growth on those trees which are especially resistant it is about 1/4 as fast as on the non-resistant stock. For non-resistant stock the seedlings on Staten Island were inoculated, and the growth on these tallied very closely with growth in non-resistant trees inoculated by Anderson and Rankin.[3]