90 DR JAMES A. GUNN ON 
Experiment 23 (figs. 6, 7, and 8).—Strength of solution, 1 in 25,000. The con- 
ditions and result of this experiment are detailed in the following table :— 
TasBLE VI.—EXPERIMENT 23, 
Time. tay eee PEE UE Solution Perfused. 
-Minute. Excursus. 
4.10 28 17 mm. Normal solution. 
4,20 30 16 ,, 
4.22 a fe Harmine solution turned on (fig. 6). 
4,25 17 11 mm. 
4,34 13 10) 5 Fig. 7. 
4.44 14 10, 
5.4 11 14 ,, Fig. 8. 
5.11 AAS sf Normal solution turned on. 
5.13 20 17 mm. 
5.16 26 his 
This solution, therefore, produced considerable slowing and some weakening of the 
heart, but did not arrest it in fifty minutes, Recovery was rapid on reperfusion with 
es 
the normal solution. 
Harrnine Hy oekbridy 
I i 25.000 . 
ae ares ee 
Fic. 6. 
TOU TIN 
Fic, 7. Fic. 8. 
These two experiments illustrate the chief effects of harmine on the frog’s heart, 
which may now be summarised. Solutions of 1 in 10,000 or more concentrated solutions 
rapidly slow the heart and arrest it in a position of complete, or almost complete, 
diastole. Solutions of 1 in 15,000 to 1 in 30,000 produce slowing of the heart, and also 
