Effect of Digitalis on Contraction of Heart. 161 



table I. 



No. 



Drug. 



Rate. 



P-R 

 Time. 



T- 

 Wave. 



Con- 

 traction. 



B-P. 



Result. 



Dogs, 19. . 



g-Strophanthin . . . 



9 



0 



0 



I 



I 



Decrease. 







8 



4 



II 



14 



4 



Increase or change. 







2 



15 



8 



4 



0 



No change. 



XI. . 



Tr. Digitalis 



4 



2 



0 



0 



0 



Decrease. 







5 



I 



6 



10 



2 



Increase or change. 







2 



8 



5 



I 



0 



No change. 



Cats, 5.. 



g-Strophanthin. . . 



3 



1 



0 



I 



I 



Decrease. 







2 



0 



4 



2 



3 



Increase or change. 







0 



4 



1 



2 



0 



No change. 



9. . 



Tr. Digitalis 



7 



0 



0 



5 



3 



Decrease. 







0 



2 



7 



2 



6 



Increase or change. 







2 



7 



2 



2 



0 



No change. 



30 dogs, the T wave changed 17 times, and remained uninfluenced 

 13 times; the degree of contraction increased 24 times; decreased 

 in 1 ; and remained unchanged 5 times. The degree of contraction 

 changed, then, in the greater number of animals; the T wave, in 

 more than half. In 14 cats, the T wave changed 11 times and 

 remained uninfluenced in 3; the degree of contraction increased 

 4 times, decreased 6 times, and remained unaltered 4 times. 

 That is to say, the T wave usually changed; the degree of contrac- 

 tion decreased in more than half. The effect on contraction 

 differed, therefore, in cats and dogs. 



In 7 dogs and 13 cats the record of the blood pressure in the 

 femoral artery was added to the other records. Except in one 

 dog and 4 cats, the blood pressure usually rose. With the tincture 

 of digitalis a significant fall of pressure often preceded a rise. 



Anesthesia and operative procedures, it was thought, might 

 disturb the electrocardiogram. Experiments were therefore done 

 on dogs in which electrocardiograms and blood pressure records 

 were taken without anaesthetic and without operation. The 

 electrocardiograms were taken in the usual way. The blood 

 pressure curves were obtained in dogs previously prepared by a 

 method described by van Leersum. By this method a long stretch 

 of one carotid artery was enclosed in a stretch of skin included 

 between two parallel incisions. The tube containing the artery 

 lay free of the neck, and surrounded by a small rubber cuff. 

 Water transmission to a mercury manometer permitted the taking 

 of records. Minimum and maximum oscillations after the manner 

 of Erlanger indicated systolic and diastolic pressures. It has 



