The first step in the development of hay fever is supposed to be a disturbance in this digestion of protein in the eyes and nose, by which larger amounts of poison are formed and absorbed by the mucous membrane, producing the first poisoning, which, like the first injection into the dog, sensitizes the mucous membrane to other doses of the same poison. It is supposed that disturbance in the protein digestion may be caused by stoppage of the nasal passages, with excessive accumulation of proteid, inhalation of excessive amounts of pollen, forming excessive amounts of poison, or, perhaps, insufficient secretion, so that the splitting-up process is not hastened to its conclusion of harmless products. The anaphylaxis theory halts a little at this point and is not exactly clear about the mechanism of that first poisoning. After the first poisoning, the epithelia are permanently injured and remain more permeable to protein. They also develop the power of making large amounts of the digesting enzyme, which is absorbed into the blood and is supplied to all the tissues of the body, so that all tissues, including the skin, can decompose the pollen protein. Advantage is taken of this distribution of the protective enzyme in the skin reaction, in which a small area of skin denuded of its superficial epithelia reacts in the form of a hive-like swelling when the pollen that originally affected the patient is brought in contact with it. The next time that the pollen reaches the eyes and nose the mucous membrane is ready for it with an abundant secretion of enzymes to destroy it. In this intense digestion of the proteid, quantities of the poisonous substances are formed which irritate the eyes and nose worse than before, explaining why hay fever becomes worse with successive attacks. The inherited form of hay fever is explained by the well-known transmission of anaphylaxis to the offspring. The first case in the line of descent must start with a severe poisoning that lays the foundation of the anaphylactic inheritance.