1. Rabbit eyes sensitized with guinea pig red blood cells or fresh egg white respond with an inflammatory reaction following the intravenous injection of the homologous antigen, but not the heterologous.
2. Two-tenths of 1.0 cc. of a multiple antigen containing ten separate ingredients, or in other words, 0.02 cc. of each foreign protein, when introduced into the rabbit's anterior chamber, is sufficient to produce an altered ocular reactivity such that when 1 cc. of one of the ten antigens is introduced intravenously the eye shows hyperemia of the iris and conjunctiva with more or less edema and lacrimation during the next 24 hours.
3. For as long as 8 months after sensitization eyes will respond with an inflammatory reaction following the intravenous injection of fractions of the total antigen.
4. Repeated daily intravenous injections of a single antigen usually produce no reaction in the sensitized eye after the first few days. Injection of different antigens intravenously on succeeding days produces a continued sterile inflammatory process in the sensitized eye. After the total number of single antigens has been injected, repetition of these injections now fails to produce a similar response. Instead, the eye reaction is at a much lower level and the inflammatory response is manifested only to a few of the antigens injected intravenously.
5. Unless massive doses of antigen are used to desensitize, permanent desensitization of the eye has not occurred in animals which have been followed for at least 8 months. Animals may develop maximal eye responses following repeated intravenous injections of the same antigen, if sufficient time has elapsed between injections. Nevertheless, the eye reactions which can be elicited 6 or 7 months after sensitization are less intense than the initial responses.
6. The ability of the eye inflammation to light up following the intravenous injection of homologous antigen is not due to an initial tissue injury as proven by the fact that the reaction is specific and anterior chambers injured with typhoid vaccine, iodine, saline, glycerine, or albolene will not respond subsequently when the various proteins used for sensitization of the other eyes are injected intravenously.
7. It has been impossible to demonstrate sensitivity in the eye by the intravenous shocking route until at least the 5th day following introduction of the antigen into the anterior chamber.
8. The eye reaction can be produced by the subcutaneous as well as the intravenous injection of antigen.
9. Rabbits vary considerably in the intensity of the eye reaction which can be elicited in them, but only rarely was an animal found which failed completely to give a reaction.