THE COMMON DENOMINATOR of all types of reversible shock appears to be an inadequate perfusion of vital visceral capillaries. This is affected, but not exclusively determined, by arterial blood pressure, cardiac output and venous return to the heart, vasoconstriction or dilitation, blood volume, heart failure, and other factors. A factor which may dramatically affect flow of blood through capillaries is the plugging of these capillaries with clotted blood. Evidence that intravascular coagulation occurs during hemorrhagic shock has been recently presented. 1 A new hemorrhagic shock model enabling the study of blood clotting factors was utilized. Under morphine sedation, dogs were bled through an ion-exchange resin column which decalcified the blood. Bleeding was carried out in 15 min. using a femoral artery catheter until the mean aortic pressure was 30 mm Hg. This usually required about 50 ml/kg. Then enough decalcified blood was returned to the animal to raise the pressure