But another and very remarkable method of mitigating the virulence of eel blood, and one which so far has received no explanation, is mentioned by Dr. Wehrmann, of Moscow, who has been lately studying the character of this fish's blood in Dr. Calmette's laboratory at the Pasteur Institute at Lille. Dr. Wehrmann found that if blood serum be taken from animals previously rendered artificially immune to the action of serpent venom, and if some of this so-called anti-venomous serum be injected under the skin of eels some hours before they are killed, the lethal properties of their blood after death are considerably reduced. Thus, an eel weighing about six ounces received subcutaneous injections of five cubic centimetres of anti-venomous serum; after the lapse of four-and-twenty hours it was killed and bled, and its serum inoculated into animals in the usual way. But whereas two cubic centimetres of normal eel blood sufficed to kill a guinea-pig, this eel's blood had to be administered in _twice_ that quantity to produce a fatal result, so that its toxic character had been reduced to a very appreciable extent. The readiness with which eel serum parts with its lethal properties, and the restricted conditions under which they can operate, sufficiently assure us that in the present state of our knowledge there is no danger to be apprehended from this fish, and in the absence of any experiments to show what is the effect on human beings of subcutaneous inoculations of such blood, there is no call for this substance to be scheduled under the Poisons Act. We have, however, by no means exhausted the extremely curious properties which characterise this material, and these properties are brought to light in a remarkable manner in connection with the investigations which have been carried out to artificially protect animals from its lethal influence, and also in some interesting experiments which have been made to compare the toxicity of eel blood with that of vipers.