168 C. G. Williams and W. H. Waters. [May 12, 



time elapsing between the placing of the foot in this stimulant and its 

 withdrawal by the animal was measured by a metronome beating 120 

 to the minute and taken as the indication of the time required for 

 reflex action. The frog was worked upon either resting on its belly 

 with its legs hanging down or suspended by its head. In order that 

 the results might not be thought due to fatigue, owing to the suspen- 

 sion of the animal, in the earlier experiments, another frog similarly 

 pithed, was suspended, and its reflex time measured simultaneously 

 with the one treated with the alkaloid. These frogs suffered no 

 change, therefore after the first experiments their use was discontinued. 



After suspension of the animal its reflex action was tested for half 

 an hour at intervals of five minutes, in order to get the length of its 

 normal reflex time. The alkaloid was then injected, sometimes pure, 

 into the stomach, and at other times dilute into the dorsal lymphatic 

 sac ; here the effect could be produced by 0*2 cub. centim. of 1 per 

 cent, solution in ten minutes to a quarter of an hour. 



The action of the /3 lutidine was most distinct, the reflex time, after 

 an interval, growing longer and longer at each stimulation, then the 

 leg would be only just removed, and that feebly from the acid ; and, 

 finally, after a time varying from a quarter to half hour the foot was 

 incapable of being withdrawn though immersed in the acid for a 

 minute or a minute and a half. 



Decidedly, then, /3 lutidine destroys reflex action in the frog. 



The disappearance of the reflex action might be attributed to the 

 following causes : — 



(1.) To the poison acting upon the heart, perhaps stopping its beat, 

 and thus cutting off the blood supply to the spinal cord. In all cases, how- 

 ever, the frog was dissected and the heart was invariably found beating. 



(2.) It might be due to its action on the nerves, thus preventing 

 the conduction of impulses to the muscles of the legs, necessary to 

 cause them to contract and withdraw the foot from the acid. 



(3.) It might be said to be due to an effect like that of urari, 

 preventing the communication of an impulse from the nerve to the 

 muscle, blocking their physiological communication. That it was not 

 due to either of these causes will be seen from the following experi- 

 ment: A frog was very carefully pithed, the sciatic nerve on each 

 side was exposed and a ligature tied round the whole of the left leg — 

 except the nerve. The nerves on each side were each stimulated with 

 such a feeble current as to cause only a slight twitching of the toes 

 (secondary coil at about 32). 



Far more (3 lutidine than is necessary to produce the described effect 

 upon reflex action was then injected into the dorsal lymphatic sac, at 

 times as much as two or more drops of the pure alkaloid being used. 

 Although the experiment lasted in some cases over two hours, the feeble 

 stimulus caused the same amount of movement in both feet as before. 



