POISONS AND THEIR PREVENTION 179 



this being one method adopted for collecting the 

 venom ; the liquid was at once dried, and 07 milli- 

 gramme was found to kill a rabbit weighing nearly 

 four pounds in four hours. Two months later on, 

 when the venom was again collected, 0*25 milli- 

 gramme proved a fatal dose. On the death of the 

 animal, at the end of eight months, the venom 

 extracted from the glands was so toxic that it only 

 required O'l milligramme to kill a rabbit of about 

 the same weight as the previous one. The same 

 curious fact was noted in the case of a cobra's 

 venom. Another circumstance which appears to 

 control the degree of toxicity inherent in serpent 

 venom is the interval of time which elapses 

 between two successive bites. The longer the 

 interval the more virulent is the venom ; and 

 Calmette points out that these observations are 

 in accordance with what has for a long time been 

 known in France with respect to indigenous vipers 

 -that their bites are far more dangerous and far 

 more fatal in the spring, after the winter period of 

 torpor is over, than in the autumn. 



Until quite recently it was thought that the only 

 creatures which could resist the fatal action of this 

 poison were serpents, both poisonous and non- 

 poisonous. Calmette was led to this conclusion 

 because, although he inoculated large doses, as 

 much as ten drops, into cobras, they suffered 



