230 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
units is sufficiently strong for therapeutic purposes. The antivenin prepared 
by Calmette had power equaling 20.000 units. Since 1895 Calmette has been 
sending out his antivenin to various laboratories in India, Cochin China, and 
Australia for trial in cases of snake bite. The antivenin is in bottles contain- 
ing 10 c.c. each. The warning is given not to use it after the lapse of one 
year from date of preparation, as its antitoxic power gradually diminishes 
with age. f 
It may be stated that Calmette employed i in his immunization of horses the 
following venoms: Cobra di capello (Naja tripudians), Trimeresurus (Lache- 
sis), Naja haje, Cerastes, Crotalus, Bothrops (Lachesis lanceolatus), Pseudechts, 
Hoplocephalus (Notechis), and different species of European vipers. The 
proportions of these venoms varied, but the venom of Naja tripudians was 
most used. 
Some cases of snake bite successfully treated with Calmette’s antivenin are 
recorded, the reports having been made by Hankin and Lepinay in Asia. 
In July, 1896, Calmette 1 read a paper concerning the treatment of animals 
poisoned with snake venom, by the injection of antivenomous serum, before 
the laboratories of the conjoint board of the Royal College of Physicians 
and Surgeons of London. It was accompanied by a series of experiments 
demonstrating the preventive and curative properties of his antivenin against 
the fatal poisoning of rabbits with cobra venom. Among others he made a 
suggestion as to the method for testing accurately and promptly the strength 
of the antivenomous serum. A standard solution of type venom must be 
placed at the diposal of the appointed experts. The toxic unit of this solution 
will be based upon the quantity of venom necessary to kill a rabbit of 2 kilo- 
grams in 20 minutes by intravenous injection in the marginal vein of the ear; 
the above quantity corresponding on the average to 0.002 gm. of cobra venom, 
weighed dried, and 0.004 gm. of crotalus venom. An antivenomous serum, 
to be sufficiently active for therapeutic use, must be a preservative in a mini- 
mal lethal dose of 2 c.c. on intravenous injection of the toxic unit of venom. 
The preventive inoculation must be made 15 minutes only before the injection 
of the venom. The testing of the serum is thus effected in less than 30 
minutes. 
Calmette and Delarde ? state that immunity against venom can be produced 
in cold-blooded animals by repeated injections of subminimal lethal doses, 
but it may not necessarily be followed by the appearance in the blood of the 
antivenomous principle in these animals, for example, in the frog. 
Calmette * published the details of his demonstrations of experimental 
serum therapy of animals poisoned with venom, as shown in London, before 
the Royal College of Physicians and Surgeons. He injected 6 rabbits (weight 
1.450 to 1.770 grams) with 3 c.c. of antivenin intravenously. After 5 hours a 
1Calmette. The treatment of animals poisoned with venom by the injection of antivenomous serum. 
Lancet, 1896, II, 449. 
2Calmette and Delarde. Sur les toxines non-microbiennes et le mécanisme de l’immunité par les 
sérums antitoxiques. Ann. Inst. Pasteur, 1896, X, 675. 
® Calmette. Sur le venin des serpents. Ibid., 1897, <a, 214. 
