730 DR FRASER ON THE PHYSIOLOGICAL ACTION 



vitality of the nerve trunk, and that this contrast in condition depends on the 

 access or not of the poison — a clear demonstration of the power of physostigma 

 to paralyse the nerve terminations. This action has been hitherto overlooked. 



Calabar bean is, therefore, now added to that very limited class of neurotic 

 agents which affect the motor endorgans. Indeed, only two substances, as far as 

 I am aware, were previously known to possess this remarkable action. For a 

 considerable time after the brilliant, and perhaps unequalled, researches of Claude 

 Bernard,* curare stood alone as such a substance : when Kolliker discovered 

 that conia has a similar action ;f and his observations have been recently 

 confirmed by Guttmann.J 



Physostigma is, however, peculiar in the method in which it so acts; a 

 very prolonged contact with the nerve terminations, and a long continued circu- 

 lation of poison-bearing blood, being apparently necessary. In warm-blooded 

 animals, this paralysis of the motor endorgans may, therefore, be easily over- 

 looked ; but in frogs, with localised poisoning, it is conspicuously displayed, as in 

 the experiments which have been given. 



It is interesting to remark the different conditions which are produced in the 

 functional vitality of nerves and muscles when physostigma is administered to a 

 frog after the vessels of one of its limbs have been ligatured. 



Experiment XXIX. 



Immediately after ligaturing the right ischiadic artery and vein of a frog, which weighed 

 609 grains, two grains of extract, in fifteen minims of distilled water, were injected into the 

 subcutaneous tissue of the back. 



One hour and twenty-five minutes afterwards, the heart was found beating seventeen times 

 per minute. 



The two gastrocnemii muscles, with their femur attachments, and a portion of each of these 

 bones, along with the sciatic nerves from their terminations in the gastrocnemii to the lumbar 

 plexus, were then removed. These parts were so arranged, that an interrupted current from one 

 Daniell's cell and Du Bois Eeymond's induction apparatus, could be transmitted simul- 

 taneously through either both nerve trunks, or both muscles, by the turn of a key. 



a. Examination of the Nerves (one hour and fifty-four minutes after the administration of the 

 poison). — The galvanic current was first passed through the sciatic nerves. Distinct tetanus of 

 the non-poisoned muscle was caused when the secondary coil stood at 63° on the scale ; the 

 poisoned was at perfect rest. The current was gradually strengthened by advancing the 

 secondary coil ; when this reached 53°, but not before, the poisoned muscle was thrown into 

 tetanus. 



b. Examination of the Muscles. — Immediately afterwards, the current was passed directly 

 through both muscles. The poisoned gastrocnemius contracted when the secondary coil 

 reached 63° ; the non-poisoned did not do so until this was advanced to between 52° and 53° : 

 that is to say, the poisoned muscle was thrown into tetanus by a weaker current than was 

 required to produce the same effect in the non-poisoned muscle. 



* Lecons sur les Sub. Tox. &c, 1857, pp. 238-413. 



t Verh. d. phys.-med. Ges. zu Wurzburg, 1859, vol. ix., part 2, p. 55, et seq.; Virchow's 

 Archiv. x., p. 235; and other papers. 



I Berliner Klin. Wochenschr., No. 5-6, 1866. Quoted in Rutherford's Report on Physiology; 

 Journal of Anatomy and Physiology, No. 1, 1866, p. 155. 



