Fic. 19.—Tracings to illustrate the influence on cardiac inhibition by vagus excitation of a small dose ot atropine sulphate 
(00054 gramme=+4, gr.) administered to a dog weighing 28 kilog. =61} lbs, 
I., tracing taken 15 minutes after the atropine was administered by injection into the pleural cavity ; II., 30 minutes 
after ; III., 45 minutes ; IV., 1 hour; V., 14 hours; VI., 24 hours after administration. 
The blood-pressure and extent of anesthetisation are approximately the same in all. 
The strength of stimulus was the same in all, and was adequate to produce strong inhibition in the absence of atropine. 
Note that this effect is abolished in 15 minutes, and does not reappear in the same form and extent during at least 24 
hours, although there is a gradually increasing amount of inhibition shown as the atropine is becoming eliminated. But 
even 23 hours after the injection the strongest stimulus (coil at 0) failed to produce any more effect than that shown in VI. 
a, blood-pressure curve ; b, respirations ; c, time in 10 secs. ; d, signal showing period of vagal excitation. 
