74 ON THE NATUKE AND ACTION OF THE 



Muscles of arms and legs exposed and irritated by single 

 induced shocks. (.r5 cm., muscles of both arms contract ; 

 muscles of both legs contract, but somewhat more strongly. 



In this experiment there is no evidence of paralysis either of 

 the nei'ves or muscles ; death appears due to paralysis of the 

 spinal cord. This is caused by the action of the poison ; for 

 the circulation still continued, though feebly, after all reflex 

 action had ceased. 



Experiment XLVIII. 



A ligature was passed under the right sciatic nerve of a frog 

 and tightly tied round the limb, so as to constrict the whole of 

 the thigh, with the exception of the nerve, and completely 

 arrest the circulation. 



At 1.8 half a drop of cobra-poison (first supply), diluted with 

 ^ c.c. of water, was injected into the dorsal lymph-sac. 



1.12. The animal is sluggish. 



1.15. Crawls about but sluggishly, and keeps the unligatured 

 limb drawn up close to the body. 



1.20. The frog is more sluggish. 



1.23. The hind limbs seem paralysed ; the fore limbs still 

 move, but much less than before. 



1.30. Frog almost motionless. Contractions of the fore limbs 

 still occur ; but they no longer respond when pinched. 



1.57. There is a faint motion in the limbs. 



2.18. Frog is dead. Much ecchymosed. 



On irritating the lumbar nerves in the abdominal cavity by 

 iin induced current, the poisoned leg contracted rather more 

 than the non-poisoned leg. 



On irritating the sciatic nerves in the thigh, below the level 

 of the ligature, the contractions of the poisoned leg were much 

 less vigorous than those of the non-poisoned leg. 



Electrodes were then placed in the spinal cord, and the cord 

 iriitated by an induced current. 



2.34. When irritation is applied in this way the fore limbs 

 contract, but not the hind limbs. 



When the cord is irritated lower dowu, the non-poisoned leg 

 responds to the irritation, but the poisoned leg does not. 



