EFFECT OF CHEMICAL AGENTS 335 



in arrest of pulsation. In fig. 177 a slight preliminary 

 exaltation of amplitude, followed by depression, may be 

 noticed. The period of succeeding pulsations is found to 

 become prolonged. 



The effect of internal application of alcohol is very 

 similar to that of external application. In fig. 178 is seen a 



Fig. 180. — Strong carbonic-acid gas, inducing arrest. Line 

 below indicates duration of application. Slow revival 

 of pulsation on substitution of fresh air. 



Fig. 181. — Effect of internal application of water charged 

 with carbonic acid. 



record exhibiting the action of a 15 per cent solution of 

 alcohol. 



Effect of Carbonic-acid Gas 



This gas when diluted with air causes an enhancement 

 of amplitude, though the period becomes longer (fig. 179). 



