OF THE CALABAR BEAN. 735 



stand, tremors, lachrymation, defecation and urination ; and in eleven minutes all respiratory 

 movement had ceased. The spinal cord was immediately exposed, but the strongest galvanism, 

 consistent with localisation of the current, applied to various portions of its substance, failed to 

 excite any movement of the body. A sciatic nerve was then exposed; and slight stimulation of it 

 produced vigorous contractions of the limb, but no reflex movement. Lastly, the thorax was 

 opened ; and the heart was found contracting thirty-two times in the minute, in perfect rhythm 

 and with regularity, although the diastolic pause was somewhat prolonged. Thirty-nine minutes 

 after death, the cardiac beats were ten per minute, and the sciatic and other nerves could 

 still transmit excito-motory impressions to their muscles. 



Such data are sufficient, after the former results, to prove the action of 

 Calabar bean on the spinal cord of mammalians, as far as it is possible to do so. 

 Where larger doses are given, the evidence is not so distinct ; as, along with com- 

 plete loss of reflex function, the heart is found paralysed at death ; and it is well 

 known that, in the animals in question, stoppage of the circulation is rapidly 

 followed by loss of reflex function. Still, from the above, and from other experi- 

 ments which will follow, it can be conclusively proved that physostigma has a 

 special and primary action on the cord. 



Experiment XXXVII. 



Performed December 1866. 

 After tying the left femoral artery and vein of a frog, weighing 430 grains, I injected two 

 grains and a-half of extract into the cellular tissue of the back. In an hour and twenty-two 

 minutes, the reflex function of the cord, as tested by stimulation of the skin by galvanism 

 and by sulphuric acid, was completely destroyed ; but the exposed heart was found acting regu- 

 larly and rhythmically, though only at the rate of twelve beats per minute. The two gastroc- 

 menii muscles, with their attached sciatic nerves, and the portions of femur into which these 

 muscles are affixed, were then removed. The poisoned nerve and muscle were arranged in the 

 usual manner on Du Bois Reymond's modification of Helmholtz's myographion — an apparatus 

 designed to measure the rates of conduction along nerve fibres. The curved lines produced 

 by stimulation of two portions of the nerve, differing in length by one inch and a-half, were 

 found to correspond so exactly that the period during which the impression travelled over the 

 one inch and a-half of poisoned nerve could not be measured. The non-poisoned nerve gave 

 the same result. 



This experiment was undertaken to determine whether physostigma gradually 

 lessens the rate of conduction in motor nerves, as curare is stated to do.* It was 

 worthless to answer this question, as was also another immediately afterwards per- 

 formed with the same result ; for the frogs employed were in too irritable a con- 

 dition : but its value is evident in considering the action of physostigma on the 

 spinal cord. For the diastaltic function of the spinal cord was completely destroyed, 

 while the poisoned and non-poisoned motor nerves were in so equally active a condi- 

 tion, that the difference between the times in which impressions travelled along two 

 portions of the same nerve, differing in length by one inch and a-half, could not be 

 measured in either, even by a delicate instrument specially adapted for this purpose. 



* A. von Bezold; Monats Bericht der Berlin: Akad. 1859. 

 VOL. XXIV. PART III. 9 



