The prominence of thrombosis in the pathogenesis of the Arthns phenomenon (1, 2), the alterations in the clotting mechanism seen in experimental anaphylaxis (3), and the occurrence of "fibrinoid" in lesions generally considered to be due to hypersensit ivity suggest tha t the interaction of antigen and antibody in vivo may in some manner init iate coagulation. Experiments to be reported here in...
