LABORATORY MANUAL OF PHYSIOLOGY. 



Bathe again with chloroform, this time undiluted. Continue 

 until the heart stops beating. In what phase does the stillstand 

 occur? How does the chloroform effect compare with that of 

 ether? How does the heart-beat change in frequency? In 

 strength? In length of diastole and systole? To which is the 

 heart more susceptible, chloroform or ether ? 



9. Suprarenal Extract (Adrenalin). Take a tracing of a 

 normally beating frog's heart. Make up a i to 10,000 solution 

 of adrenalin chlorid in physiological saline. Bathe the heart 

 with this solution and record results. What is the effect on the 

 strength and frequency of the heart-beat? Upon systole and 

 diastole ? 



Place the web of the frog's foot under the microscope. Locate 

 certain vessels whose outlines are quite distinct. Add a few drops 

 of the adrenalin solution to the web and note the effect upon the 

 calibre of the vessels. 



IX. PERFUSION OF FROG'S HEART. 



Pith a frog and expose the heart. Excise the heart, including the 

 sinus venosus. With sharp-pointed scissors make an opening in 

 the auricles. Introduce, through this opening, Kronecker's perfu- 

 sion cannula into the ventricle. Secure the cannula by means of a 

 ligature tied above the base of the ventricle. Connect one limb of 

 the cannula with the perfusion tube and the other with the small 

 frog's-heart manometer (see Fig. 29). 



Allow the heart to hang in the normal saline bath. Connect this 

 with one pole of a dry cell. Connect the other pole with the bind- 

 ing post on the cannula. Interpose a key in the circuit. The heart 

 may stop beating for several minutes after the cannula is tied in. 

 The beats, however, will generally begin spontaneously after a 

 short time. If not, closing the key of the constant current, and 

 thus stimulating the heart, will probably be sufficient to bring 

 about rhythmical pulsations. Simple distention of the ventricle 

 with the perfusing fluid may be enough of a stimulus. 



Fill one perfusion tube with o.6-per-cent NaCl solution and the 



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