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DR. T. L. BRUNTON AND MR. W. PYE ON THE ACTION 
The reflex excitability was then tested at intervals of 5 minutes by irritating points 
above and below the ligature. No difference in the sensibility could be detected. 
As the frog was very little affected by the injection, another § cub. centim. was 
injected. 
The frog became insensible to reflex irritation in five and twenty minutes ; during this 
time the irritability was tested every five minutes as before ; the rates of increase of the 
insensibility appeared to be equal above and below the ligatures. 
In this experiment the poison was applied to the terminations of the sensory nerves 
above the ligature, but not to those below it. Had it possessed any marked power of 
diminishing the sensibility of these nerves a stimulus applied above the ligature would 
have had less effect than one applied below it ; but this was not the case. 
The poison therefore seems to have no action on sensory nerves, at any rate none of 
a paralyzing character. 
Action on Reflex. 
Experiment LIII. 
In this experiment the action on reflex was tested by applying a very dilute solution 
of sulphuric acid to the leg of a frog with its cerebrum destroyed and suspended by its 
head. Its normal irritability was then tested. The tips of the toes only were immersed 
in the acid. Contraction was immediate and lasted three minutes (right leg). A £ cub. 
centim. alcoholic solution was then injected ; the animal immediately hung more 
flaccidly. Five minutes afterwards, on immersing the tip of the toes of the right leg, 
slight contraction occurred after 63 seconds. A quarter of an hour later, on immersing 
half the leg, contraction was immediate and lasted 5 seconds ; in ten minutes more a 
similar immersion produced contraction after 10 seconds, and five minutes afterwards 
after 15 seconds. Fifty minutes after the injection of the drug the acid solution 
produced no reflex movements, and only slight ones were excited by pinching. 
Reflex ceased last in the eyelids one hour and twenty minutes after the casca had 
been injected. 
In Experiment LIII. the reflex excitability disappeared very much more quickly than 
it usually does. 
This might be due to the action of the drug on the spinal cord itself, or to the cessa- 
tion of circulation caused by the action of the drug on the heart. 
In order to decide this the following experiment was made. 
Experiment L1Y. 
The heart of a frog was exposed and casca administered. As soon as the heart had 
ceased to beat the heart of a second frog was ligatured at the root of the aorta so as 
completely to arrest the circulation. At first both frogs were able to jump readily ; but 
gradually their movements became more sluggish, and after a jump their legs trailed 
out behind them and were only slowly drawn up to the body. They became less and 
