The author's object was, 1st, To confirm and extend the investigations of Gruby concerning the mycodermatous vegetations growing in the crusts of the cutaneous disease called Porrigo lupinosa;—2d, To describe a plant he had himself found growing on the living membrane and tubercular matter of Phthisis pulmonalis;—3d, To describe the structure of a plant found infesting the skin and gills of the gold-fish;—and, 4th, To inquire into the pathological state which furnishes the conditions necessary for the growth of fungi in living animals.