22 Dr. C. Bolton. Physiological Action of a [Mar. 20, 



marked rise in arterial blood pressure, both when the vagi were divided and 

 when they were intact. 



This result proves that the rise of blood pressure is due to a direct 

 stimulation of the muscular coats of the arterioles. There is no evidence to 

 show that the vaso-motor nerves are in the least affected by the poison. 



Action upon the Frog's Heart. 



When applied to the frog's heart the effect of the poison is to gradually 

 diminish the size of the beats till the ventricle is brought to a stand-still in 

 diastole, the auricle continuing to beat for a little while longer and then also 

 stopping in diastole. 



Sometimes a block is seen at the auriculo-ventricular junction, only every 

 second beat crossing over, and occasionally irregular peristaltic waves, com- 

 mencing at the base, pass over the ventricle. The ventricle may take on an 

 independent rhythm. The rate of the heart is not altered until just before it 

 stops, when slight slowing is noticed. 



Application of atropine to the heart in arrest fails to restore its action, 

 thus showing that the standstill is due to a direct action on the muscular 

 tissue of the heart and not to stimulation of the terminations of the vagus. 

 The same result is seen if the atropine is applied before the poison. 



If the heart be thoroughly washed with Einger's solution, its action may 

 be restored, if it has not completely come to a standstill. If the sinus be 

 stimulated with an electric current when the heart has stopped, the action 

 may be temporarily restored. 



Action upon the Voluntary Muscle of the Frog. 



The poison was applied to the muscle with a brush, and at each application 

 the muscle shortened very slightly. The nerve was stimulated with an 

 induced current and the poison continuously applied until the muscle failed 

 to respond to the stimulus. The muscle itself was now stimulated, and 

 entirely failed to respond to any strength of current. 



This proves that the muscular tissue itself is paralysed by the poison. 

 The experiment, of course, does not prove that the poison does not at the 

 same time act upon the nerve ends, but the object of this experiment was to 

 prove whether or not the muscular tissue itself was paralysed. 



6. Conclusions. 



The poison selects muscular tissue for its action and there is no evidence 

 whatever that it produces any action upon the central or peripheral nervous 



