114 ON THE NATURE AND ACTION OF THE CROTALUS-POISON 



" 2nd. In cases where animals or men have been poisoned by 

 the bite of vipers, such as the Russell's viper. 



" 3rd. In all cases of snake-bite, whether from the poisonous 

 colubrine or viperine genera, in the human subject.* 



" The blood undergoes cither partial or complete coagulation 

 under the following conditions : — 



" 1st, When a small quantity only of the cobra-poison has been 

 injected into a vein or an artery. 



" 2nd. In cases where the lower animals have been bitten by 

 the cobra. 



" Why the admixture of a large and quickly fatal injection of 

 the cobra-virus into the circulation of animals should produce 

 comparatively permanent fluidity of the blood or interfere with 

 its ordinary coagulability soon after removal from the body or 

 after death, and why the injection of a smaller and more slowly 

 fatal quantity should interpose no obstacle to its speedy coagu- 

 lation, are questions extremely difficult to account for or 

 explain. We can only state the fact that, in the one case, 

 coagulation occurs sj)eedily, and in the other this coagulation is 

 retarded or altogether prevented by some cause at present 

 unknown." 



The following experiments were made on the physiological 

 action of the virus of the rattlesnake, with the view of com- 

 parison with that of the cobra and Dahoia. 



We are indebted to Dr. Weir Mitchell, of Philadelphia, for a 

 supply of the virus. He was good enough to send about 

 six grains of the dried poison of Crotalus — the species not 

 named, but it is believed to be of Crotalus durissus. 



The dried poison supplied is said to be about 6| years old^ 

 and was dried in July or August at the natural temperature, 

 and has since then been preserved in a phial. It was tried by 

 Dr. Mitchell, and found active three years ago. 



It has the appearance of fractured fragments of dried gum- 

 arabic, of rather a darker yellow colour, but otherwise resembling 

 the dried cobra-virus sent from Bengal. 



* Not always so. — J. Fayrer, 



