314 Dr. L. Eogers. On the Physiological [June 6, 



After the final failure of the circulation the sciatic nerves were tested 

 with an interrupted induced current, and stimulation of both the 

 nerves and the muscles directly caused contractions, showing that the 

 smaller dose of poison used in this experiment had not caused paralysis 

 of the end plates, although after the final cessation of artificial 

 respiration no convulsions followed the rise in blood pressure. This 

 points to complete exhaustion of the respiratory centre, occurring 

 before paralysis of the end plates, having been the cause of the 

 .absence of terminal convulsions. 



The repeated lowering of the blood pressure and disappearance of the 

 commencing convulsions following immediately upon the performance 

 of artificial respirations go to show that the rise of blood pressure and 

 the convulsions are secondary in nature to the paralysis of the 

 respiratory centre, and due to the increasing venosity of the blood. 

 Further, it is evident that the poison has no powerful direct paralysing 

 effect on the heart itself, as is the case with Pseudechis venom. The 

 result of the above experiment is also of interest in connection with 

 one by Vincent Richards,* in which a dog was bitten by an Enhy- 

 drina, and artificial respiration was kept up for 24 hours and 35 

 minutes after the failure of respiration, sensibility being restored, and 

 at the same time convulsions recurred, pointing to partial recovery of 

 the respiratory centre from the condition of complete paralysis. Death 

 finally occurred by accidental arrest of artificial respiration. In his 

 experiment the dose given was a small one, as respiration did not 

 cease until after two hours, but it is evident that the poison exerted 

 no injurious action on the heart. 



Action on Newes and End-Plates. 



Brunton and Fayrerf first showed that Cobra venom exerts a para- 

 lysing action on the muscles' end-plates like curara ; this was confirmed 

 by Ragotzi,| and the last- mentioned observer attributed the failure of 

 respiration tojparalysis of the end-plates of the diaphragm. We have 

 already seen (Experiment 5) that a similar motor nerve paralysis may 

 result from Enhydrina poisoning, so that it is necessary to inquire 

 whether this is due to an effect on the nerve trunk or on the end-plates. 

 If the nerve trunk is itself poisoned, so as to lose its power of con- 

 ductivity, then the negative variation of the current of injury should be 

 greatly reduced or entirely abolished by very dilute solutions of the 

 venom. This has been tested by Dr. Waller's method by placing the 

 sciatic nerves of frogs in dilute solutions of the venom, and measuring 

 the negative variation of the current of injury with a galvanometer 

 both before and after exposure to the poison. The nerves were first 



* ' Indian Medical Gazette,' 1873, p. 119. 

 f ' Eoy. Soc. Proc.,' vols. 21, 22, and 23. 

 J ' Virehovv's Archiv,' vol. 122, p. 232. 





