Summary: The immediate reactions between specific foreign protein and anaphylactic blood are in themselves usually insufficient to cause recognizable anaphylactic phenomena in normal dogs. If the liver of an anaphylactic dog is transplanted into a normal dog, the normal dog will show all of the characteristic features of canine anaphylaxis on intravenous injection with specific foreign protein. If specific foreign protein is injected into a mesenteric vein of an anaphylactic dog and shock blood collected as it escapes from the liver, this blood, transfused into a normal dog, will reproduce all of the characteristic features of canine anaphylaxis. Blood drawn from the carotid artery from two to five minutes after throwing a dog into anaphylactic shock, usually shows little or no toxic action, when transfused into a normal dog The hepatic anaphylatoxin is not the only factor operating in canine anaphylaxis.