112 ON THE NATURE AND ACTION OF THE CROTALUS-POISON 



points of difference sufficiently characteristic to require notice 

 in detail. 



We have already expressed our belief that death is caused by 

 the cobra-, Daboia-, and Hydrophis-^oimn, 1st, through its action 

 on the cerebro-spinal nerve-centres, especially on the medulla, 

 inducing paralysis of respiration ; or, 2nd, in some cases (where 

 the poison has entered the circulation in large quantities and 

 has been conveyed more directly to the heart) by arrest, tetani- 

 cally in systole, of cardiac action, probably owing to some action 

 on the cardiac ganglia ; 3rd, by a combination of the two 

 previous causes ; 4th, by a septic condition of a secondary 

 nature, and which, being more essentially pathological in its 

 bearings, the details were not considered suitable for discussion 

 here. 



There is reason to believe that death is caused in the same 

 way by the Crotalns-^^oimn also ; and it appears, from the 

 experiments recently performed in Calcutta, by Dr. Ewart and 

 the members of the Committee appointed by Government, upon 

 Fseudechis porphyriacus, or the black snake, and Hojplocephalus 

 curtus, or the tiger-snake of Australia, that their virus causes 

 death in the same manner. These reptiles had been sent from 

 Melbourne to Calcutta for the purpose of investigation and com- 

 parison. ( Vide Committee's Eeport, pp. 58 et seq., Appendix.) 



But though the actual cause of death is essentially the same, 

 the phenomena which precede and accompany it differ in some 

 degree according to the nature of the poison, the quantity and 

 site of the inoculations, and the individual peculiarities of the 

 creature inoculated, as may be seen in the experiments herewith 

 recorded. 



The condition of an animal poisoned by the rattlesnake- 

 venom, then, essentially resembles that of one subjected to the 

 influence of the colubrine or viperine poison of Indian 

 snakes : — 



Depression, hurried respiration, exhaustion, lethargy, un- 

 consciousness, nausea, retching, and vomiting {vide experiment 

 on cat. Experiment IX). 



Muscular twitchings, ataxy, paralysis, and convulsions (the 

 latter probably chiefly, though not entirely, due to circulation 



