I have been able to prove that the _antineurotoxic_ property of antitoxic serums with regard to the venoms of COLUBRIDÆ is pretty much on a par with their antihæmolysing property, so that it is possible to measure _in vitro_ the antitoxic activity of a serum by establishing the degree of its antihæmolysing activity. Thus we see that a serum, which is antitoxic and antihæmolytic with respect to the venom of _Naja_, is likewise antihæmolytic as regards the other COLUBRINE-venoms, and even certain venoms of VIPERIDÆ. Here we have a very important fact, for it enables us to measure _in vitro_ the activity of antivenomous serums. (2) _Precipitins of Venoms._--The serum of rabbits treated with increasing doses of _Cobra_-venom precipitates the latter in more or less concentrated solution. It has no effect as regards other venoms. On the other hand, the serum of a strongly immunised horse, the antivenomous power of which was pretty considerable, gave no precipitate with _Cobra_-venom; the formation of precipitate is therefore entirely independent of that of antitoxins (G. Lamb).[52] (3) _Agglutinins of Venoms._--Besides their hæmolytic action, it is easy to observe that certain venoms, especially those of VIPERIDÆ, agglutinate the red corpuscles, and that the substance that produces this agglutination is different from the hæmolysing substance; for it acts rapidly at a temperature of O° C., at which hæmolysin manifests its effects only with extreme slowness. Heating to 75° C. destroys this agglutinant property (Flexner and Noguchi). C.--EFFECTS OF VENOM UPON THE WHITE CORPUSCLES: LEUCOLYSIN. The white corpuscles themselves do not escape the action of venom. It is possible _in vitro_ to prove this action upon leucocytic exudations obtained, _e.g._, by injecting sterilised cultures of _Bacillus megatherium_ into the pleura or peritoneum of the rabbit. After a few hours this exudation is removed by means of capillary tubes, and, on mixing these with weak doses of venom, we see, in the course of a microscopic examination, that the large mononuclear cells are the first to be dissolved, then the polynuclears, and lastly the lymphocytes. The leucolysis is much more intense and more rapid with _Cobra_-venom than with that of _Crotalus_ (Flexner and Noguchi, Noc). CHAPTER IX. _PHYSIOLOGY OF POISONING_ (_continued_). PROTEOLYTIC, CYTOLYTIC, BACTERIOLYTIC AND VARIOUS DIASTASIC ACTIONS OF VENOMS: DIASTASIC AND CELLULAR ACTION ON VENOMS. A.--PROTEOLYTIC ACTION. The proteolytic action of venoms on gelatine, fibrin, and egg-albumen has been studied by Flexner and Noguchi,[53] Delezenne,[54] and subsequently by Noc[55] in my laboratory. It was already known that _in vivo_ certain venoms exert a manifestly dissolving action on the endothelium of blood-vessels and on the muscular tissues themselves.