74 



ELEMENTARY PHYSIOLOGY. XIII. 



clamp on the tubing, and take a tracing of the heart- 

 beat for a minute or two. Then drop into the cannula 

 | to 1 c.c. of -001 p.c. adrenaline. The heart-beat will 

 gradually increase in force and frequency. As the heart 

 pumps out the fluid the effect of the adrenaline will 

 gradually pass off. 



4 in. 



Fig. 23. 



2. The effects of arecoline and atropine should be simi- 

 larly determined if they were not observed in Less. XII. 

 Observe the effects of the following variations in the 

 percentage of salts in the fluid used for perfusion. In 

 each case, a tracing of the heart-beat is taken using 

 Ringer's fluid for perfusion. The india-rubber tube from 

 Mariotte's bottle is then clamped (the new fluid may be 

 injected into its peripheral end to wash out the Ringer's 

 fluid), and the new fluid dropped into the cannula. 



