In a previous communication to this Society, tbe present authors showed that the rapid intravascular injection of " peptone " into cats, deprived of hepatic activity, inhibited coagulation of the blood. It was also shown that when precautions are taken to preserve the surface conditions of the blood of the cat, pronounced retardation of clotting can be obtained in vitro by the addition of " peptone " in quantities no greater than are required to produce a like effect in vivo (Pickering and Hewitt, 1). Subsequently, Nolf (2) observed that the anti-coagulant action of " peptone " on the blood of the domestic fowl, with the liver extirpated, is actually greater than in the intact animal. Experimenting with the blood of dogs, Doyon (3) found that nucleic acid, prepared by Neumann's method (4) from the thymus and from the mesenteric ganglia of the ox, is anticoagulant in vivo and in vitro, the former reaction being ascribed to the supposed secretion, by the liver, of an antithrombic nucleoprotein.In this paper the action of W itte's peptone on the coagulability of the blood of the tortoise, rat and dog, and that of thymus and yeast nucleic acids, is described and discussed. In each experiment, except where otherwise stated, the blood was obtained from animals with the liver out of circulation.
I . -Technique and Terms Employed.The mammals used were anaesthetised with A.C.E., pithed, and artificial respiration was employed for at least 10 minutes prior to injection of either peptone " or of nucleic acid. The tortoises were anaesthetised with chloroorin aud decapitated after clamping the vessels of the neck. The mammals ^ere deprived of hepatic activity by ligature of the thoracic aorta and inferior Veua cava> the tortoises by ligature of the bulbus arteriosus and sinus venosus.Blood was shed through evenly paraffined cannulae into clean glass vessels, m quantities of 1 c.c. or less at a time, as blood shed in small quantities does Uot exhibit the hyper-coagulability which arises from excessive haemorrhage.on May 9, 2018 http://rspb.royalsocietypublishing.org/ Downloaded from