56 ON THE NATURE AND ACTION OF THE 



due to an affection of the central ganglia. More especially may 

 the occurrence of convulsions be thought to exclude the 

 possibility of death being due to paralysis of the peripheral 

 terminations of motor nerves ; for if tlieir function is abolished 

 here, how, it may be said, can general convulsions, which have 

 their origin in the nervous centres, occur ? 



The answer to this is, that although the ends of the motor 

 nerves are so far deadened that they no longer transmit to the 

 muscles any ordinary stimulus proceeding from the nerve- 

 centres, their function is not so thoroughly abolished that they 

 cannot transmit those which are stronger than usual. This is 

 shown by the fact that when an animal is slowly poisoned by 

 curare (as for example when that poison is introduced into the 

 stomach after ligature of the renal vessels), convulsions occur 

 just as in death from cobra-poison. Although the motor nerves 

 have their function so much impaired that they no longer 

 transmit to the muscles of respiration the ordinary stimuli from 

 the medulla, which usually keep up the movements of 

 breathing, they can still transmit those stronger impulses which 

 proceed from it when greatly stimulated by the increasing 

 venosity of the blood, and which cause the respiratory as well 

 as the other muscles of the body to participate in the general 

 convulsions. The loss of co-ordination which occurs in poisoning 

 by cobra-venom has also been noticed by Voisin and Liouville 

 in poisoning by curare. 



That the peripheral terminations of the motor nerves are 

 actually paralysed by cobra-venom is shown by Experi- 

 ment XXXVI, in which the animal was able to move the leg 

 which had been protected from the action of the poison for 

 some time after the rest of the body was perfectly motionless, 

 as well as by Experiment XXXVII and those succeeding it. 

 Its occurrence in man is indicated by the symptoms of a case 

 described by Dr. Hilson {Ind. Med. Gaz., October, 1873, p. 254). 



But paralysis of motor nerves is not the only effect of cobra- 

 poison on the nervous system. The spinal cord is also 

 paralysed, as is seen from Experiment XLI, where motion 

 ceased in the frog's leg which remained free from poison, 

 although it answered with great readiness to a very weak 



