THE PHARMACOLOGICAL ACTION OF HARMINE. 89 
ox-blood (one part) and Ringer’s solution (two parts) was used as the nutrient 
solution and as the solvent for harmine. The bulb of the plethysmograph which 
contained the heart was filled with Ringer’s solution, and the contractions of the ventricle 
were recorded by means of an air-piston recorder attached by a rubber tube to the brass 
cylinder. 
Experiment 22 (figs. 3 to 5).—Strength of solution, 1 in 10,000. This strength of 
Systole = 
HAT 
Fic. 3. 
Normoet Olsed, Slution 
12° 3% 
Fic. 4. 
Fic. 5. 
solution rapidly reduced both the rate of beat of the heart and also the amplitude of 
its excursus, the diminution of excursus being due mainly to less complete systole, 
but also to incomplete relaxation (fig. 3). Thus, in three minutes the rate fell from 18 
to 6 contractions per minute, while the excursus was reduced from 9 to 2 millimetres. 
In six minutes the ventricle was arrested in a position of almost complete diastole, and 
the normal solution was thereupon substituted for the harmine solution (fig. 4). This 
so quickly restored the heart, that in ten minutes the rate and the excursus were 
practically the same as before harmine (fig. 5). 
