belonging to the class of Ascomycetes; and that these spores, inserted by themselves under the bark, produced the same pathological changes as did the pieces of gum.  The fungus thus detected, was examined by Professor Oudemans, who ascertained it to be a new species of Coryneum, and has named it Coryneum Beijerincki.  The inoculation experiments are best made by means of incisions through the bark of young branches of healthy peach trees or cherry trees, and by slightly raising the cut edge of the bark and putting under it little bits of gum from a diseased tree of the same kind.  In nearly every instance these wounds become the seats of acute gum disease, while similar wounds in the same or other branches of the same tree, into which no gum is inserted, remain healthy, unless, by chance, gum be washed into them during rain.  The inoculation fails only when the inserted pieces of gum contain no Coryneum.  By similar inoculations similar diseases can be produced in plum, almond, and apricot trees, and with the gum of any one of these trees any other can be infected; but of many other substances which Beijerinck tried, not one produced any similar disease.  The inoculation with the gum is commonly followed by the death of more or less of the adjacent structures; first of the bark, then of the wood.  Small branches or leaf stalks thus infected in winter, or in many places at the same time, may be completely killed; but, in the more instructive experiments the first symptom of the gum disease is the appearance of a beautiful red color around the wound.  It comes out in spots like those which often appear spontaneously on the green young branches of peach trees that have the gum disease; and in these spots it is usual to find Coryneum stromata or mycelium filaments.  The color is due to the formation of a red pigment in one or more of the layers of the cells of the bark.  But in its further progress the disease extends beyond the parts at which the Coryneum or any structures derived from it can be found; and this extension, Beijerinck believes, is due to the production of a fluid of the nature of a ferment, produced by the Coryneum, and penetrating the adjacent structures.  This, acting on the cell walls, the starch granules, and other constituents of the cells, transforms them into gum, and even changes into gum the Coryneum itself, reminding the observer of the self-digestion of a stomach.

In the cells of the cambium, the same fluid penetrating unites with the protoplasm, and so alters it that the cells produced from it form, not good normal wood, but a morbid parenchymatous structure.  The cells of this parenchyma, well known among the features of gum disease, are cubical or polyhedral, thin walled, and rich in protoplasm.  This, in its turn, is transformed into gum, such as fills the gum channels and other cavities found in wood, and sometimes regarded as gum glands.  And from this also the new ferment fluid constantly produced, and tracking along the tissues of the branches, conveys the Coryneum infection beyond the places in which its mycelium can be found.