Of the various theories suggested as to the mechanism of traumatic shock, two have recently received most attention, viz: (1) that of the absorption of metabolic toxins from the traumatized area with secondary generalized vasodilatation and increased permeability of the capillaries, a theory advocated by Cannon,1 Cannon and Bayliss,2 and others, and (2) that of the local loss of blood or plasma, or both, resulting in a serious decrease in the volume of circulating blood, as supported by the work of Blalock,3 Phemister and co-workers,4 Freedlander and Lenhart5 and others. Various investigators (Mason and Lemon,6 Carlson, Woelfel and Powell,7 Popielski8 and Bayliss9) have shown that extracts of many tissues contain substances which depress the blood pressure, and this fact has been frequently cited10 in support of the "toxic theory" of traumatic shock. Carlson, Woelfel and Powell,7 however, after examining