ACTION OF ALCOHOL 135 



reaches a place directly over the first inhibition record, 

 stimulate the vagus nerve again. Do you now get an in- 

 hibition, or has the drug paralyzed some part of the local 

 inhibitory apparatus? Drop on more alcohol and again 

 stimulate the nerve over the second inhibitory record. The 

 total length of the record from left to right should be 

 about seven or eight inches with a moderate drum speed. 

 About five or six rounds of tracing (in a series from the 



w^ 





Fig. 127. Injecting pipette made of glass. About 2/3 natural size. 



bottom of the drum upwards) should be made. Add the 

 alcohol freely to the heart during the second and third 

 rounds, but on the later rounds, if necessary, use thirty or 

 forty per cent alcohol. What is the general action of alco- 

 hol on the frog's heart as shown by your tracing? Does 

 alcohol either paralyze or stimulate the inhibitory appa- 

 ratus'? How does this compare with ether or chloroform 1 ? 



EXPERIMENT XI. 



Alcohol. (Turtle: Heart and Vagus Nerve.) 



1. Pith a turtle and fasten it down to the turtle board. 

 Expose the heart and take a heart tracing (normal) includ- 

 ing two or three vagus inhibitory records. Then apply 

 twenty per cent alcohol to the heart as was done in Experi- 

 ment X, and again stimulate the nerve. What effect does 

 the drug have on the local inhibitory apparatus'? If the 

 heart muscle alone should be stimulated by the drug would 

 the inhibition be greater or less when the nerve was stim- 

 ulated after the drug was applied? How would the inhibi- 

 tion be affected if the muscle alone were depressed? 



