The current theories as to the initiation of traumatic shock have been reviewed so often and so well1that it will not be necessary to repeat them. In 1919, Cannon and Bayliss2traumatized the thigh muscles of cats and other animals, thus producing a prolonged lowering in the blood pressure, which they ascribed to a toxin originating in the traumatized area. Since that time, the toxic theory of traumatic shock has become widely accepted. The actual experiments reported were few, and the data were scanty. The original theory was based largely on the analogy to shock produced by histamine. Since that time many others have worked on the problem, with the result that there has been practically no positive evidence of toxemia, while there has been considerable direct negative evidence. The argument for toxemia rests largely on the presumptive exclusion of other factors, the chief of which are