DR THOMAS R. FRASER ON" STROPHANTHTTS HISPIDUS. 397 



for several minutes in extreme diastole before it ultimately ceased to contract, with the 

 ventricle large and dark. 



In the two latter experiments, also, although there was so great a predominance of 

 ventricular diastole, the systolic contractions of the ventricle were very strong and 

 complete during the greater portion of each experiment. 



The reaction of the heart's muscle was examined in two only of these experiments. 

 It was found to be acid in one of the experiments (LXXVI.) in which the systolic effect 

 predominated, and neutral, or nearly so, in one of the experiments (LXXVII.) in which 

 the diastolic effect predominated. 



Cardiograph Tracings with Small and Large Doses respectively. 



Several experiments were made for the purpose of obtaining graphic representations 

 of the changes produced in the heart's contractions by Strophanthus. It was found a 

 comparatively easy matter to represent the changes produced by the application of such 

 doses as cause an exaggeration of the ventricular systole ; but difficulty was encountered 

 in obtaining tracings representative of exaggeration of the ventricular diastole, as the 

 tendency of even slight mechanical irritation, such as that produced by light pressure 

 upon the heart, is to divert the diastolic into the systolic type of change. 



The plan adopted was to place the small metal plate of a Marey's cardiograph, 

 provided with a very light glass lever-rod, on the ventricle of the exposed heart of a 

 pithed frog. Large German frogs {Rana escvlenta) were used, and care was taken to 

 place the metal plate of the cardiograph accurately upon the surface of the ventricle, 

 avoiding especially any contact with the auricles. The free distal extremity of the glass 

 rod was so adjusted as to record its excursions, with as little friction as possible, on a 

 revolving cylinder covered with smoked glazed paper. In some of the experiments the 

 brass plate resting upon the ventricle became displaced by the movements of the heart ; 

 but, in order to avoid any fallacies that might be caused by failure in accurately 

 replacing the plate in its original position, these experiments have been excluded, and 

 only those are recorded in which the plate retained exactly, or nearly exactly, its original 

 position throughout the experiment. 



The first of these experiments, with its tracings, illustrates the type of action in 

 which systole predominates. 



Experiment LXXIX. — Weight of frog (Rana esculenta), 1160 grains. 0'00375 

 grain of strophanthin in 0'05 per cent, solution ( = 0*000323 grain per 100 grains) 

 applied to the heart in divided doses during 3 hours 9 min. (Plate XIII.) 



11 a.m. Frog pithed. 



3.45 p.m. Cardiograph applied. 



3.51. Tracing No. 1. 



3.54. Applied to the heart \ minim ( = 0-00025 grain) of ahove strophanthin solution. 



4.20. Tracing No. 2. 



4.21. Second application of strophanthin solution, \ minim ( = 0-00025 grain). 



