272 



VENOMOUS ANIMALS 



that the serum of an animal vaccinated by snake-venom contained 

 antitoxins capable of producing an immunity in new animals. 



Calmette obtained his serum from horses, but with great diffi- 

 culiy, as many of the animals died in the course of treatment from 

 endocarditis and acute nephritis, while in others abscesses formed. 



He found that in a fresh horse 0-025 gramme of cobra-venom 

 was sufficient to kill the animal in twelve to twenty-four hours, 

 but on vaccinating the animals for sixteen months, it was found 

 that a horse could stand without reaction the injection of 2 grammes 

 of cobra-venom — i.e., eighty times the M.L.D. 



From such a horse it was found possible to withdraw as much as 

 20 litres of blood in three bleedings spread over ten days, the serum 

 being considered to be ready for use when i c.c. mixed with o-ooi 

 gramme of cobra-venom produced no sign of intoxication when 

 injected subcutaneously into a rabbit, and when, after injecting 

 2 c.c. of the serum into a rabbit of 2 kilogrammes weight, two 

 hours later i milligramme of venom could be injected without 

 results. This serum was said to preserve intact its antitoxic value 

 in all climates. The venom used for these injections was principally 

 that of the cobra, with a slight admixture of other venoms. 



In 1895-96 Fraser of Edinburgh confirmed Calmette's results, and 

 believed that if an animal was so successfully vaccinated that it 

 could resist the minimum lethal dose of one venom, it would also 

 be able to resist that of other venoms. He believed that venom 

 introduced into the stomach conferred immunity. 



In 1897 C. J. Martin showed that Calmette's serum did not 

 preserve animals against the venom of Notechis scufatus. 



From 1901 onwards Lamb in India studied carefully the effects 

 of snake-venoms, and came to the conclusion that Calmette's serum 

 is active against cobra-venom, but is not useful against that of 

 Viper a russellii, Bungarus fasciatus, or of Echis carinaUis. 



In 1902 Tidswell showed that serum prepared from the venom 

 of Notechis scutatus did not neutralize the venoms of the cobra, 

 Bungarus fasciatus, or Vipera russellii, and, further, had no effect 

 on the venoms of the brown and black snakes and death-adder of 

 Australia. 



In the same year Lamb pointed out that there was a precipitin 

 m venom-immune sera, and this point being further investigated by 

 Hunter, the deduction was made that these precipitins were specific, 

 and due to the coagulable proteids. 



The following pure sera have been prepared : — 



1. Lamb's Pure Naja tripudians Merrem Serum. — This serum 

 is strongly antitoxic for cobra - venom, and in large doses for 

 Enhydrina valakadien Boie, but has no effect upon Bungarus can- 

 didus L., Brachyaspis curta Schleg., Echis carinatus Schn., Lachesis 

 gramineus Shaw, Vipera russellii Shaw. 



It delays death in Bungarus fasciatus Schn., Naja bungarus 

 Schleg., Crotalus durissus L. 



2. Lamb's Pure Vipera russellii Shaw Serum. — This serum 



