The recent work by Dunbar1 on the cause and specific treatment of hay fever is bound to excite great interest among medical men. Dunbar seems to successfully show that the pollen of a great variety of cereals and grasses—rye, oats, wheat, corn, grasses—contain substances that in susceptible individuals, but only in the susceptible, produce the well-known phenomena of hay fever. And these pollens produce hay fever, no matter how or where or when introduced. The active substance is soluble in tears, saliva, nasal secretion and blood serum. Even the hypodermic injection in susceptible persons of the starch rodlets in the pollens mentioned has caused severe conjunctivitis, coryza, cough and asthmatic seizures. These results would seem to settle the cause of hay fever, although the nature of susceptibility or unsusceptibility remains as yet wholly obscure. Dunbar, then, undertook the production of a curative serum by following the principles of immunization.