Many fundamental questions regarding immunobiological reactions are as yet unanswered. However, certain working principles have been reached through long observation and research, and the terms foreign protein reactions, complement, precipitins, antibodies, anaphylaxis, etc., have acquired definite and specific significance. Attempts have been made to fit these concepts to clinically observed phenomena, but to date the so called pollen sensitizations have never been satisfactorily elucidated on an immunological basis. Many observers have noted the wide variations in the clinical results of therapy. Others have questioned the expectation of any significant effects from the injection of so little real protein in desensitization and have found it difficult to correlate this desensitization and clinical improvement with a skin test persistently positive to the specific atopic agent. The apparent inability to obliterate these hypersensitivities, as well as their frequent multiplicity are problems as yet unexplained.Efforts at solving these problems have resolved themselves into (a) attempts to sensitize animals and reproduce the syndrome observed in human beings (1); (b) the study of Dale preparations of uterine strips taken from sensitized guinea pigs (2); (c) efforts to sensitize animals by upper air passage or intratracheal insufftation (1); (d) the investigation of serum reagins by Prausnitz-Kfistner reaction and by precipitin tests (3); (e) studies of results of therapy in clinical cases of atopic hypersensitiveness (4). These investigations are well known to readers of the literature on the subject. As with all biological experiments the results have been inconstant, or the methods introduced elements into the problem not germane to the investigation at hand.