Considerable interest is attached to the fact that anti-venomous serum not only acts as an anti-toxin towards serpent venom, but also towards a poison of quite a different character, such as that present in the normal blood of eels, for this fact tends to confirm the view upheld by some authorities, that specific toxins do not necessarily only yield to specific anti-toxins, and that a particular anti-toxin may act as such towards divers toxins of varied origin and character. Calmette has brought this point out very clearly in his later investigations on the vegetable poison abrine, a very powerful toxin, furnished by the active principle of the seeds or beans of a leguminous plant common in India and South America, and frequently used, as already mentioned, by the natives in India to revenge themselves on their enemies in poisoning their cattle. Immunising serums of various kinds were selected for testing their protective action on animals poisoned with abrine, and it was found that anti-tetanic, anti-diphtheritic, anti-anthrax, and anti-cholera serums all individually exerted a decided immunising action with regard to this powerful vegetable poison. The hope is, therefore, perhaps not beyond the realm of possibility, that at some future time the complexity of drugs which now figure in the chemists' pharmacopoeia may be replaced by a few substances the application of which will come within the means and understanding of all. So far we have not dealt with the artificial immunisation of an animal from the action of eel poison, but this apparently offers very little difficulty, and is accomplished by introducing very small and gradually increasing doses of eel serum into the system, care being taken to proportion the quantity given according to the weight and general condition of the animal to be immunised. A rabbit, for example, treated in the above manner, subsequently yielded a serum which was proved to possess both preventive and curative powers in respect to both eel poison, and viper venom and blood, entitling this so called anti-eel serum to take its place amongst the anti-toxins, and furnishing yet another instance of a substance exercising its immunising influence over various toxins. This process of gradually acclimatising, as it were, animals to a particular poison by repeated doses of the same poison, recalls the old proverb, "Seek your salve where you got your sore," and brings us to a consideration of some of the primitive antecedents of a practice which, at the present time, promises to bring about so profound a revolution in the art of medicine. The modern system of inoculation has, however, arisen quite without reference to such antecedents, which latter were not based upon any scientific laws or considerations, but owed their evolution to local customs and experience handed down from age to age by tradition, and in many cases preserved through a simple faith in the superstitions which surrounded them.