Bi JAMES M. PETKIE. 



345 



Exp. 7. — Dog, weight 9450 gms. 

 Action on Respiration. 



The arterial pressure curve showed a rise of blood-pressure iuitnediately 

 following the first and second injections, but not the third. The last injection 

 was followed by a sudden drop, and after 1.5 minutes by a rise to a still higher 

 level. 



Summary of Results. 



When very small doses of the alkaloid were administered to animals, in these 

 experiments, a complete change was observed in the heart-rhythm and respira- 

 tions. 



Blood-pressure. — During the few seconds required to run in th« solution, 

 the blood-pressure rose, and quickly reached a maximum. This was soon 

 followed by a drop, which, however, never reached the previous normal level 

 but rapidly rose again and remained high till near the end when it rapidly 

 fell to zero. 



Heart-heats. — In one frog alone the heart-beats were accelerated; in the 

 other frogs the number was decreased. The dog in experiment 5 showed a 

 large increase after the injection. 



Respiration. — In experiment 5 after an injection of 2.5 milligrams tlie 

 number of respirations gi-adually decreased during the 12 minutes, from 27 to 

 per minute. In No. 6 experiment 1 milligram injected produced an increase 

 in number, but after a second and third injection the number gradually lessened, 

 and ceased after 13 minutes. In No. 7 experiment 0.5 milligram accelerated the 

 respirations, and after a second and third injection still further accelerations 

 were observed. One minute after the last, the number decreased, and 7 minutes 

 later the respiration ceased. 



The chief characteristic of the drug is, therefore, its action on the heart- 

 muscle. The tone is increased, heart relaxes less during diastole, and in the 

 later stages the heart-beats become very irregular. The heart in most cases 

 eomes to a standstill in systole. 



Convulsive movements were observed in the animals towards the end of the 

 experiments. 



