The mechanism of hay-fever is worthy of careful study for the reason that hay-fever is quite typical of the great group of clinical conditions presumably due to a natural sensitiveness to some foreign substance. This sensitiveness is termed allergy. Up to the present time at least, allergy has been recognized only in man. A tendency to it is often inherited. It manifests itself by different symptom complexes each quite characteristic whenever the individual comes in contact with the specific foreign substance.
When this contact is by way of the respiratory tract, the symptoms are usually referable to disturbances in the nose and the patient is said to have hay-fever. This hay-fever may be either seasonal or perennial. Seasonal hay-fever would appear to be a very clear cut disease with a definite and well defined etiology, because the symptoms begin and end at the exact time when the particular pollen appears
RACKEMANN FM. THE MECHANISM OF HAY-FEVER. Arch Intern Med (Chic). 1922;30(2):221-228. doi:10.1001/archinte.1922.00110080091006