2. The primary reaction, which becomes manifest approximately 3 days after inoculation and lasts several days, is characterized by a diffuse clouding of the cornea. During this period, no antibody can be demonstrated either by serological or histological techniques. The animals react with a delayed type of skin reaction and the sensitivity can be passively transferred to normal guinea pigs with the cells of pooled lymph nodes or buffy coats. The corneal reaction is therefore considered a manifestation of delayed sensitivity.

3. The secondary reaction in the cornea, usually occurring about the 14th day after inoculation is the "Wessely phenomenon." This reaction is characterized by a precipitation of immune complexes in the cornea resulting in a visible annular corneal opacity. Circulating antibody can be readily demonstrated by both serological and histological techniques and the animals demonstrate typical Arthus skin sensitivity.

4. Generally intervening between these two phases of corneal activity is a stage in which the inoculated eye appears essentially normal. This stage is eliminated if both corneas are inoculated initially.