1903.] Action of the Poison of the Hydrophidce. 311 



a less marked degree by Brunton and Fayrer,* when large doses of 

 Cobra venom are introduced directly into the circulation. (In small 

 doses, subcutaneously administered, Cobra venom has very little action 

 on the heart, which can be kept going for many hours after spontaneous 

 respiration has ceased by means of artificial respiration, as shown by 

 the Indian Snake Poison Commission.)! 



I have examined this point by testing if the poison has any paralysing 

 action on the heart of a pithed frog, tracings being taken of the con- 

 traction of the organ before and after the direct action of solutions of 

 the poison of various strengths in normal saline solution. As a few 

 drops of a l-in-1000 solution of Enhydrina poison given per venam, 

 and therefore further greatly diluted in the circulation, is very rapidly 

 fatal, it is evident that the poison should produce a very marked action 

 on the heart when directly applied to it if the lethal effect is in any 

 degree due to cardiac paralysis. My experiments have shown that 

 such is not the case, for a l-in-1000 solution when directly applied to 

 a vigorous frog's heart produced no appreciable effect in any of several 

 trials : a 1 -in- 100 solution, similarly applied on two occasions, did not 

 retard, still less arrest the action of the heart. 



Effect of Artificial Respiration on the Blood Pressure and tlie Heart. 



The absence of any direct paralytic effect of Endydrina poison 

 on the heart was also shown by an experiment of another kind. As 

 already mentioned, the heart can be kept going by artificial respiration 

 for a very long time in Cobra poisoning, but this is not the case 

 with poisoning with the venom of the Pseudechis ; C. J. Martin J 

 has shown that the heart fails within a very few minutes after cessa- 

 tion of spontaneous respiration, in spite of artificial respiration, in the 

 case of the last-named snake poison, which also has a marked direct 

 paralytic action on the heart. In the following experiment artificial 

 respiration was started directly marked failure of respiration appeared 

 and the blood pressure had begun to rise, and the effect of repeatedly 

 stopping and recommencing it on the blood pressure was rioted. 



Experiment 4. 



Cat, 3J kilos., under chloroform. Cannula in the carotid artery, 

 connected with a Gad's manometer. Eespirations recorded with 

 a Sandstrom's instrument. 7 milligrammes (2 milligrammes per 

 kilo., weight) in 1-75 c.c. 0'9 per cent. NaCl injected into the 

 jugular vein. 



* 'Boy. Soc. Proc.,' vols. 21, 22, and 23. 



f ' Indian Medical Q-azette/ 1873, p. 119. 



J ' Roy. Soc. of New South. Wales Proc./ 1896. 



