OF THE CALABAR BEAN. 729 



paralysis and death in mammals, or of complete loss of voluntary power in frogs. 

 The next question which suggests itself for solution is the somewhat interesting 

 one of the portion of nerve acted on; for, in the case of more than one toxic 

 substance, it has been determined that loss of motor nerve-function does not 

 of necessity imply that both the periphery and nerve-trunk have been affected. 



Experiment XXVII. 



Immediately after ligature of the left ischiadic artery and vein, two grains of extract were 

 placed in a subcutaneous cavity at the back of an active large frog. Before twenty minutes, 

 respiratory movements had ceased; while the heart was then acting rhythmically, at the rate of 

 thirty beats per minute. One hour after the administration of the poison, the right (or poisoned) 

 sciatic nerve was exposed, and found active ; but in other twenty minutes, strong galvanism 

 applied to any portion of its trunk could not produce contractions in the muscles to which it 

 was distributed, and an examination of the brachial nerves proved them also to be paralysed. 

 The left sciatic nerve was, however, perfectly active. When it was galvanised, movements, 

 confined to that limb, were produced in the muscles below (or distal from) the ligatures. 

 These ligatures were on the thigh; but stimulation of the nerve above them, or of the lumbar nerves 

 on the same side, vjas followed by energetic muscular contractions below the points of ligature. 



The muscles were everywhere active, and continued so for several days ; and those of the 

 non-poisoned limb were the first to pass into rigor mortis. The sciatic nerve of the non- 

 poisoned limb, and the lumbar nerves of the same side, continued active for many hours; but 

 their loss of function occurred several hours before that of the muscles below the ligatures. 



This evidence, which has been frequently confirmed, is in favour of the view 

 that the motor paralysis caused by physostigma is due to an action on the nerve 

 endorgans, or peripheral terminations, and not to one on the trunk. We may 

 obtain even more distinct proof, by a slight modification of this experiment. 



Experiment XXVIII. 



An incision was made down the centre line in the right posterior extremity, from the back 

 of the knee to the ankle, of a frog, weighing 876 grains; and in this way the gastrocnemius 

 muscle was completely exposed. It was carefully dissected from its connections, excepting that 

 its origin and insertion, and the nerve fibres entering it, were untouched. All its blood-vessels 

 were ligatured, and the cut through the skin was closed by sutures. 



Immediately after the above operative procedure, three grains of extract, in fifteen minims 

 of water, were injected under the skin of the back. Reflex movement could not be excited 

 an hour and five minutes afterwards, while the heart still continued to contract. Both sciatic 

 nerves were then exposed. Galvanism of the left produced no contraction ; while galvanism 

 of the right caused energetic movements of the limb, which, moreover, did not extend to 

 the toes. Five hours after the administration of the poison, this condition continuing, the 

 left gastrocnemius was exposed, and the right again laid bare by cutting the sutures. 

 Galvanism of the right sciatic demonstrated visibly contraction of the right gastrocnemius, 

 but of no other muscles of that limb ; and no result followed stimulation of the left sciatic, 

 although the left gastrocnemius muscle contracted vigorously when the poles were applied to 

 its surface. 



It is thus shown that some of the endorgans of a motor nerve may have 

 their conductivity destroyed while others remain active during the retained 



