1. Epinephrin when injected into a dog or cat intravenously in doses of 0.9 mgm. per kilo causes an increase in number of erythrocytes of 1.5 to 2.0 millions per cubic millimeter of blood in from five to ten minutes, lasting about one half hour and then gradually returning to normal (see fig. 1).
2. Removal of the stomach, intestine, mesentery, omentum, pancreas and spleen, either singly or all together has no appreciable effect on this reaction to epinephrin (see fig. 2).
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3. A head thorax animal does not respond to epinephrin (see fig. 3).
4. The addition to the head thorax animal of the liver, supplied by arterial blood only, gives an animal which responds to epinephrin (see fig. 4).
5. In an animal in which all arterial blood supply to the liver is shut off by ligation of the hepatic artery (the portal circulation being left intact), epinephrin causes no increase in number of erythrocytes. But if one half hour or later, after the injection of epinephrin, arterial blood is again allowed to reach the liver by removal of this ligature, the number of erythrocytes is immediately increased as if a fresh dose of epinephrin had been injected into the animal (see fig. 5).
6. In an animal in which the arterial blood supply to the liver is shut off by ligation of the hepatic artery, the injection of epinephrin into the portal vein causes an immediate increase in number of erythrocytes (see fig. 6).
7. Removal of the liver from the circulation by ligation of the hepatic artery and shunting the portal blood around the liver by means of an Eck fistula, gives an animal in all respects normal except for the absence of the liver. Epinephrin injected intravenously into such an animal causes no increase in number of erythrocytes per unit volume of blood (see fig. 7).
8. Finally neither emotional stimuli as rage and fear, or the intravenous injection of epinephrin, causes an increase in number of erythrocytes per unit volume of blood in the rabbit (8), which animal differs from the cat and dog, as shown by Mautner and Pick (9) in that the capillaries of the liver in the rabbit do not constrict with epinephrin, while those of the cat and dog constrict when the slightest amount of this substance is perfused through them.