COMMON VIPER. 65 



backwards, and the head fixed almost horizontally. In 

 an instant the head is, as it were, launched by a sudden 

 effort towards the object of its anger, and the erected tooth 

 struck into it, and withdrawn with the velocity of thought. 

 It is found by experiment that the effect of subsequent 

 wounds is greatly diminished either by the diminution of 

 the quantity of venom, or by some deterioration of its 

 strength ; so that if a venomous Serpent be made repeat- 

 edly to inflict wounds, without allowing sufficiently long 

 intervals for it to recover its powers, each successive bite 

 becomes less and less effective. A gentleman of my ac- 

 quaintance had some years since received a living Rattle- 

 snake from America. Intending to try the effects of its 

 bite upon some rats, he introduced one of these animals 

 into the cage with the Serpent ; it immediately struck the 

 rat, which died in two minutes. Another rat was then 

 placed in the cage ; it ran to the part of the cage farthest 

 from the Serpent, uttering cries of distress. The Snake 

 did not immediately attack it; but after about half an 

 hour, and on being irritated, it struck the rat, which did 

 not exhibit any symptoms of being poisoned for several mi' 

 nutes, and died at twenty minutes after the bite. A third, 

 and remarkably large rat, was then introduced into the 

 cage. It exhibited no signs of terror at its dangerous 

 companion, which, on its part, appeared to take no notice 

 of the rat. After watching for the rest of the evening, my 

 friend retired, leaving the Serpent and the rat together; 

 and on rising early the next morning to ascertain the fate 

 of his two heterogeneous .prisoners, he found the Snake 

 dead, and the muscular part of its back eaten by the rat. 

 I do not remember at what time of the year this circum- 

 stance took place, but I believe it was not during very hot 

 weather. 



