BT JAMES M. PETKIE. 



343 



After the second application of alkaloid solution thf rhythm of the heart 

 changed. The systolic contractions were slightly increased. The beats were 

 slower, iind the continued widening of the curve, produced by the prolongation 

 of the period of diastolic pause, was enormously drawn out near the end, till 

 the final systolic contraction remained permanent. 



In another experiment with the frog heart the number of beats decreased, 

 and this was accompanied by an increase and lengthening of the diastolic 

 pkase. The ventricle remained full of blood when the heart had ceased to beat. 



In the diagram, parts of this record are shown. The top line shows the 

 commencement of the experiment, the second line after 10 minutes, the third 

 line after 20 minutes, and the fourth line the end at 30 minutes. 



(c) Action on Dogs. 



The animals were anaesthetised by ether vapour. The blood pressure in the 

 left carotid artery was recorded on the kymograph, and also the respirations by 

 a stetiiograph drum fixed on the chest. The alkaloid, in the form of a saline 

 solution of the hydrochloride, was injected from a burette into the right jugular 

 vein. The concentration of this solution was equivalent to 1 milligram of alka- 

 loid in each cubii- centimetre of 0.9% physiological salt solution. 



Exp. 5.— Dog, weight 3800 gms. 



Time- 

 inrterval 



Observations. 



Normal records 



Ran in 2 5 mgs. of alkaloid during 

 16 sees. 

 Max. blood-pressure observed. 



Min. blood-pressure obser\-ed. 



Blood-pressure began to fall. 

 Heart-beats very irregular. 



The time was reckoned from the completion of the injection. 



The action of the alkaloid was almost instantaneous. 2.5 milligrams were 

 injected, and before the last drop had entered the arterial pressure had risen 

 cousideral)ly. The maximum pressure was reached 20 seconds after the end of 

 the injection. The immediate result of the injection showed the blood-pressure 



