Naja tripudians 0.00047 Naja hagé 0.0003-0.0007 Acanthophis antarctica 0.001 Ceraste 0.0017-0.0021 Haplocephalus variegatus 0.0025 Trigonocephalus 0.0025 [144] CALMETTE: _Annal. Instit. Pasteur_, VIII, p. 276; IX, p. 229. =Nature of Serpent-venoms.=--These venoms are homogeneous liquids, somewhat more dense than water, in which they are soluble, slightly colored green or yellow, transparent, and insoluble in alcohol; they contain from 30 to 35 per cent. of solid matter. When fresh, they have a slightly acid reaction. Towards chemical reagents, and particularly acids, they behave like albuminoids; almost all the combinations they afford with the various albuminoid reagents are active, despite their insolubility. According to Gautier, they are decomposed by caustic potash. According to numerous researches, oxidizers like potassium permanganate, the hypochlorites, hydrogen peroxide, and gold chloride (in 1% solution) destroy the venoms; in certain cases when immediately injected hypodermically in the poisoned region, these substances are excellent antidotes _in vivo_.[145] [145] WINTER and BLYTH: _The Analyst_, 1877, p. 204; LACERDA: _Compt. rend. de l'Acad. des Sciences_, XCIII, p. 466; CALMETTE: _Annal. Instit. Pasteur_, VI, p. 175, and VIII, p. 278. We shall not here enter upon a detailed study of the toxic albuminoid principles of serpent-venoms; moreover, our knowledge is rather vague, as it is, on a number of points. It will suffice us to know that, taken altogether, the active albuminoids of these venoms are numerous, and that each venom has its own particular active constituents, differing according to the species and variety of the snake. Each one of these substances acts more or less rapidly, and may be associated with different principles which give rise to the variability of the action of these toxic agents. Among these toxic albuminoids, the most virulent appear to be true albumins and globulins, followed by the nucleo-albumins, as we have already stated; there are also found in venoms alkaloidal bases, but these principles are present only in very slight quantity. These bases are but very slightly toxic compared with the toxins that accompany them. =Natural Immunity towards Serpent-venoms.=--Certain animals exhibit a natural immunity toward snake-bites; among them are the snakes themselves, the hog, the hedgehog, and the mongoos (an Egyptian rat); the blood of these animals contains apparently an antitoxin.[146] [146] _Compt. rend. de l'Acad. des Sciences_, CXXI, p. 745; JACODOT: _Arch. de Médecine Navale_, VII, p. 390.