STROPHANTHUS SARMENTOSUS : ITS PHARMACOLOGICAL ACTION. 369 



succeeding closures of the eyelids immediately after the application of the solution of 

 the extract. 



From these experiments it appears that the extract is capable of abolishing the 

 sensibility of afferent nerves for a considerable time, and of diminishing it for several 

 hours longer. Subsequently, there is complete recovery of the function of these nerves. 

 Slight dilatation of the pupil accompanies the anaesthesia of the surface of the eyeball. 



(c) Motor Nerves. 



Among the general effects following the administration of lethal doses of the 

 extract, it was noted repeatedly, especially in the rabbit, that soon after death galvanic 

 stimulation of motor nerves failed to cause contraction of the muscles they supplied, 

 while the muscles themselves, when stimulated directly, still responded to moderately 

 strong galvanic stimuli. The experiment already described (Experiment XLV.) in 

 connection with the examination of the effects upon the spinal cord shows, in addition, 

 some of the effects of S. sarmentosus upon motor nerves. 



The results of that experiment are as follows : — The heart was finally arrested 

 within 25 minutes of the injection ; the spinal reflex had disappeared within 1 hour of 

 injection ; galvanic stimulation over the spinal cord produced extension of the lower 

 extremities within 2 hours, but had no effect after 3 hours ; galvanic stimulation of 

 the sciatic nerve within 3 hours was effective on the unprotected side, and within 

 3^ hours it was quite ineffective ; on the protected side similar stimulation pro- 

 duced contraction of the gastrocnemius 3f hours after the injection ; direct galvanic 

 stimulation of the gastrocnemius caused contraction of the muscle on either side 3 hours 

 15 minutes after the injection ; and failed to cause contraction on the unprotected side 

 in 3 hours 20 minutes, but still caused contraction on the protected side after 4 hours. 

 It is evident that, on the side exposed to the action of Strophanthus, the motor nerves 

 conduct impulses after the spinal reflex has disappeared, but that galvanic stimulation 

 of the poisoned nerves fails to produce contraction of their muscles while the poisoned 

 muscles themselves still respond to direct galvanic stimuli ; and, further, it is seen that 

 those motor nerves which are protected from the effects of the extract preserve the 

 power, when electrically stimulated, to cause their muscles (also protected) to contract, 

 not only for some time after stimulation of the unprotected nerves has become in- 

 effective, but even for a considerable time after the poisoned muscles have ceased to 

 respond to galvanic stimuli. 



To investigate the action on motor nerves further, a series of experiments was 

 performed with nerve-muscle preparations consisting of the frog's gastrocnemius with a 

 long piece of the sciatic nerve attached. The nerve- trunk of one preparation was placed 

 in a suitable vessel with the muscle of a second preparation, while the muscle of the 

 first preparation and the nerve of the second occupied a contiguous vessel. One of 

 these vessels contained Ringer's solution, and the other a solution of the extract in 

 Ringer's solution. By means of a single bichromate cell and a Du Bois Reymond's 



