The author categorizes the widely observed superficial slime formation in the plant kingdom into three categories, which he examines in detail and describes extensively in this work. The classification includes the category of free-moving plants that live in water or are attached to a wet substrate, plants in the process of growth where superficial slime formation occurs on various parts, and superficial slime formation that is associated with both water and other parts belonging to the plant itself. This work is a high-quality reprint of the original edition from 1899.