OF THE CALABAR BEAN. 727 



any usual irritant, of continuance of the diastaltic function of the cord ; but the heart was now 

 contracting nine times in the minute. The sciatic nerves were then exposed ; and, on galvanis- 

 ing either of them, movements occurred in, and were confined to, the muscles of the limb whose 

 nerve was so stimulated. Both nerves continued to give this evidence of the conductivity of 

 their motor fibres as long as one hour and thirty-eight minutes after the injection of Calabar 

 bean, or one hour and twenty-four minutes after all respiratory movements had ceased. Shortly 

 afterwards they were found paralysed. 



Experiment XXIII. 



Into the lower portion of the abdomen of a frog, which weighed 620 grains, a mixture of 

 two grains of extract with ten minims of distilled water was injected. In twelve minutes, 

 the frog was lying in a flaccid condition, and respiration had ceased. In two hours, no reflex 

 movement could be excited. The right sciatic nerve was exposed; and its motor conductivity 

 was found to remain. Galvanism, applied to either sciatic nerve, produced muscular contrac- 

 tions in the limb to which the nerve was distributed, until, but not later than, three hours and 

 twenty-one minutes after the administration of the poison, or three hours and nine minutes 

 after respiration had ceased, and until more than one hour and twenty-one minutes after 

 apparent destruction of the reflex function of the spinal cord. In this experiment, it is important 

 to note, the cardiac action was not greatly affected for more than three hours, as the dose of 

 poison administered was comparatively small. 



Experiment XXIV. 



Six grains of extract, suspended in fifteen minims of distilled water, were injected into the 

 abdominal cavity of a frog, weighing 350 grains. In eight minutes, no cardiac impulse could 

 be discovered ; and the heart was then exposed and found motionless, dark and flaccid. 

 Respiratory movements ceased in eight minutes. It was determined, on irritating the skin 

 with sulphuric acid, that reflex movements could not be obtained two hours and a-half after the 

 injection; but they were produced until nearly this time. The motor conductivity of the sciatic 

 nerves was retained for twenty-nine hours. 



It thus appears that the motor nerves always remain active after the co- 

 ordinated movements of respiration have ceased, and after the condition of 

 complete and flaccid paralysis has existed for long. On this point, therefore, 

 I cannot agree with Harley, who considers that physostigma is a respiratory 

 poison only, and that the early production of asphyxia is caused by paralysis of 

 the motor nerves.* 



The protracted interval in the last experiment, between the administration of 

 the poison and the loss of motor conductivity, must be looked upon as a very 

 exceptional one, and as due to the poison having so quickly paralysed the heart 

 that the usual phenomena were not produced. In Experiments XVII., XIX., 

 XXL, XXII., and XXIII., the motor nerves appear to have lost their function 

 sooner than naturally happens in death from cardiac paralysis or from asphyxia. 

 But that they really did so must have remained a mere impression, had it not 

 been that we can, in frogs at any rate, definitely prove a special action on the 



* Journal de 1'Anatoraie et de la Physiologic, 1864, p. 141, et seq. ; and British Medical 

 Journal, Sept. 3, 1863. 



VOL XXIV. PART III. 9 M 



