188 



CHAPTER VIII. 



PHYSIOLOGY OF PQISONING {continued). 



Action of Venoms on the Blood. 



On making an autopsy of an animal which has succumbed- to 

 intoxication by snake-venom, we find that the blood in thd heart 

 and large vessels is sometimes coagulated into a mass, sometiines 

 entirely fluid, and that, in certain cases, it is as black as prune- 

 juice, while in others it is of a fine transparent red colour. 



These differences in the effects of venom upon the blood are 

 due to the fact that the various venoms contain in variable pro- 

 portions, besides the neurotoxic substance which represents the 

 true venomous toxin, other substances which act, some upon the 

 plasmasia or fibrin-ferment, or upon the fibrin, others upon the 

 red corpuscles, others on the leucocytes, and others again on the 

 endothelium of the blood-vessels. 



A. — Effects of Venom on the Coagulation of the Blood. 



It was observed long ago by Fontana^ that after viper-bites 

 the blood remains fluid, and Brainard^ on the contrary, pointed 

 out that, in the case of animals that succumb very rapidly after 

 having been bitten by a Crotalus, the blood was always found 

 coagulated into a mass, while, when a certain interval of time 

 had elapsed since the bite, it remained fluid. Weir Mitchell' 



' Fontana, " On Poisons," translated by J. Skinner : London, 1787. 



' Smithsonian Beports, 18.54. 



' Smithsonian Contributions to Knowledge, 1860. 



