"If 1 mgr. of cobra-venom, or 4 mgr. of viper-venom, be mixed, in a test-tube, with a small quantity of serum from an immunised rabbit, and a fresh rabbit be inoculated with this mixture, it does not suffer any discomfort. It is not even necessary that the serum should come from an animal vaccinated against the same sort of venom as that in the mixture. _The serum of a rabbit immunised against the venom of the cobra or the viper acts indifferently on all the venoms that I have tested._" In 1894 he had prepared enough serum for the treatment to be tried by his own countrymen practising in some of the French colonies. In April 1895, he gave the following account of his work:-- "I have immunised two asses, one having received 220 mgr. of _naja_-venom from 25th September to 31st December 1894, and the other 160 mgr. from 15th October to 31st December. The serum of the first of these two animals has now reached this point, that half a cubic centimetre destroys the toxicity of 1 mgr. of _naja_-venom. Four cubic centimetres of this serum, injected four hours before the inoculation of a dose of venom enough to kill twice over, preserve the animal in every case. It is also therapeutic, under the conditions that I have already defined; that is to say, if you first inoculate a rabbit with such a dose of venom as kills the control-animals in three hours, and then, an hour after injecting the venom, inject under the skin of the abdomen 4 to 5 cubic centimetres of serum, recovery is the rule. When you interfere later than this the results are uncertain; and in all my experiments the delay of an hour and a half is the most that I have been able to reach. "This antivenomous serum of asses has these same antitoxic properties with all kinds of snake-venom; it is equally active _in vitro_, preventive, and therapeutic, with the venoms of _cerastes_, of _trigonocephalus_, of _crotalus_, and of four kinds of Australian snakes that Mr. MacGarvie Smith has sent to M. Roux. I am still injecting these two animals with venom, and I hope to give to their serum at last a much greater antitoxic power." In 1896 four successful cases of this treatment in the human subject were reported in the _British Medical Journal_. In 1898 Calmette made the following statement of his results:-- "It is now nearly two years since the use of my antivenomous serum was introduced in India, in Algeria, in Egypt, on the West Coast of Africa, in America, in the West Indies, Antilles, &c. It has been very often used for men and domestic animals (dogs, horses, oxen), and up to now none of those that have received an injection of serum have succumbed.... A great number of observations have been communicated to me, and not one of them refers to a case of failure." (_British Medical Journal_, 14th May 1898.)