DR THOMAS R. FRASER ON STROPHANTHUS HISPIDUS. 401 



Summary of Changes 'produced in the Heart's Action. 



The evidence derived from the experiments in which the changes produced by Stroph- 

 anthus in the heart's movements have been specially observed, appears to show that : — 



1. A systolic type of change is produced by large doses and a diastolic by small 



doses. 



2. Whatever be the type, great increase occurs in the movements of the heart, by 



exaggeration of expansion as well as of contraction. This occurs only tempo- 

 rarily where the type is systolic, but throughout, or nearly throughout, the 

 action where the type is diastolic. 



3. Slowing of the rate of contraction is always produced. In the systolic type of 



action, by prolongation of ventricular systole, and by actual pauses in extreme 

 systole ; in the diastolic type, by prolongation of diastole, and by pauses in 

 extreme diastole. 



4. The auricular expansions and contractions are increased as well as the ventricular, 



and most obviously where the type is the diastolic one. The pumping capa- 

 bility of the whole heart, and not merely of the ventricles, is therefore increased, 

 especially when non-lethal or small lethal doses are administered. 



5. The production of this increase in the movements of the heart, constituted by a 



greater amplitude of diastolic expansion and a more complete systolic contrac- 

 tion, is significantly emphasized when the action of Strophanthus is produced 

 in an enfeebled and insufficiently acting heart, as in Experiment LXXXI. ; and 

 this experiment is therefore of peculiar value in demonstrating the therapeutical 

 value of Strophanthus in heart disorders. 



6. In the systolic type of action, the reaction of the muscle of the heart rapidly 



becomes acid, indicating that Strophanthus acts on the heart muscle in the 

 same way as on the skeletal muscles ; in the diastolic type of action, on the 

 other hand, the muscle of the heart is neutral or it may remain alkaline, even 

 for a considerable period of time after paralysis of the heart has been induced. 



II. Energy of Action on the Heart. 



Many of the preceding experiments have shown that very minute doses of Stroph- 

 anthus are able to modify the contractions of the heart. They do so with an energy 

 sufficient to cause arrestment of the heart's contractions, when, for instance, the Tooth 

 part of a grain of strophanthin is administered to a rabbit, and the joWth part of a grain 

 to a frog, by subcutaneous injection. 



Although these doses are undoubtedly very minute, still more striking evidence of 

 this great energy of the action upon the heart has been obtained in a further series of 

 experiments, in which extremely dilute solutions of extract and of strophanthin were 



