1903.] Action of the Poison of the Hydrophidce. 319 



plates of the muscles of the upper extremities were not paralysed, 

 points to a diminution of the reflex functions of the spinal cord. On 

 the other hand, the marked reflex contraction of all four limbs on 

 applying a strong current to the eye just after respiration had ceased, 

 shows that the reflex functions of the cord were not abolished at this 

 period, although they rapidly declined within a few minutes of 

 complete respiratory paralysis, as would be expected. The less rapid 

 affection of the motor end-plates of the upper extremity, as compared 

 with those of the lower limbs, accounts for the ascending paralysis 

 apart from any interference with the functions of the spinal cord 

 itself. 



We must conclude, then, that the respiratory paralysis is complete 

 before the reflex functions of the spinal cord are abolished, although 

 they may be diminished at an earlier stage, so that the action of 

 Enhydrina poison on the spinal cord itself is of quite secondary 

 importance as compared with the paralysis of the respiration and of 

 the motor end-plates of the muscles. 



Conclusions. 



1. In lethal doses, Enhydrina poison has no direct depressing action 

 on the heart. The marked rise in blood pressure observed is secondary 

 to failure of respiration, producing venosity of the blood. 



2. The primary action of the poison is the production of a respiratory 

 paralysis by a direct action on the respiratory centre, this being very 

 quickly followed by paralysis of the end-plates of the phrenic nerves. 

 The latter may occur at a time when the sciatic nerves show no end 

 plate paralysis. 



3. The poison has a very marked action in paralysing the end-plates 

 of motor nerves, but does not perceptibly affect the conducting powers 

 of the nerve trunks themselves. In this respect it resembles Cobra 

 venom and curara. 



4. Its action on the reflex functions of the spinal cord is slight, and 

 altogether secondary in importance to its influence on respiration. 



