CHAPTER II

IMMUNITY IN MULTICELLULAR PLANTS 29 Infective diseases of plants.—Plasmodia of the Myxomycetes and their chemiotaxis.—Adaptation of the plasmodia to poisons.—Pathogenic action of _Sclerotinia_ upon Phanerogams.—The cicatrisation of plants.—Defence in plants against Bacteria.—Sensitiveness of vegetable cells to osmotic pressure.—Adaptation of plants to modifications of osmotic pressure.—Dependence of the chemical phenomena upon the irritability of the vegetable cells.—The law of Weber-Fechner.