The poison of the scorpion serves it to kill the insects which are its prey. Frogs and birds stung by the scorpion also generally die. A dose of 0.0005 Gm. kills a guinea-pig in less than one hour; and according to Calmette[163] less than 0.0005 will kill a white mouse in two hours. Oxidizers destroy the toxicity of the poison. Guinea-pigs immunized against the poison of the scorpion resist perfectly very large doses of the poison. [163] CALMETTE: _Annal. de l'Instit. Pasteur_, X, p. 232. =Poisonous Blood and Serums.=--It is an almost general fact that the blood and blood serum of batrachians, eels, lampreys, snakes (even non-poisonous ones), and hedgehogs are very poisonous. Mosso has found in the blood serum of the lamprey a toxin possessing a strong hemolytic power, and which he has named _ichthyotoxin_. O.5 Cc. of this serum injected into a dog kills it in a few minutes. He also observed, in 1888, that the blood of the eel, in like dose, kills a dog almost immediately, and that the blood contains an ichthyotoxin analogous to that of the lamprey. This substance, which appears to be closely allied to the sero-albumin of the blood, has a phosphorus-like, sharp, and burning taste. By digestion it loses its toxicity, as well as by heating at 68° to 70° C. It is easily obtained by precipitating with ammonium sulphate the serum of eels, and dialyzing the precipitate dissolved in water. The power of this substance is almost as great as that of the cobra poison, 0.002 Gm. being instantly fatal per kilo of dog. The blood of snakes is likewise very toxic; the same is true of the blood of the viper, as 0.02 Cc. will kill a guinea-pig in two hours. All these bloods lose their toxicity when heated above 70° C. The serum of the hedgehog is peculiar in this respect; when heated at 38° C. for fifteen minutes it loses its toxicity, but it then possesses an immunizing power against the poisons. The subject possesses great interest, because it was in studying these immunizing properties that Camus and Gley,[164] and later on Kossel[165] and Tchistowitch,[166] discovered the first anticytotoxin,[167] which they obtained by treating the animals with increasing quantities of the serum of eels. On mixing the antitoxic serum of these animals _in vitro_ with the red blood-corpuscles of the species furnishing the serum and of the hemolytic serum of eels, it is found that the blood-corpuscles kept quite well. [164] _Archives internat. de Pharmacodynamie_, III and IV. [165] _Berliner Klin. Wochenschr._, 1895, No. 7. [166] _Annal. de l'Instit. Pasteur_, XIII, p. 406.