362 Dr. Richardson on the possibility of [June 15, 



flat ion. I believe it myself to be due to the action of the external air, which 

 at a moderate temperature gives up a little oxygen to the blood in the walls 

 of the heart, by which some heat is evolved and therewith motion is exhi- 

 bited. My reasons for this view rest on the facts that a current of air at 35 

 Fahr., brought to bear on the heart, at once stops the action, while another 

 current above 60 restores it, and that a little vapour of chloroform or of 

 ammonia blown upon the heart both of which agents stop oxidation im- 

 mediately arrests the action, which returns, at a sufficient temperature, when 

 these agents are lost by diffusion. I believe also that the right auricle is last 

 to die, because its thin walls allow the passage of oxygen to venous blood on 

 their interior, since on washing out the auricle thoroughly with water, or 

 on applying to it a substance which prevents oxidation, the auricular motion 

 at once declines. 



These remarks on the effect of artificial respiration in relation to the 

 motion of the heart, do not apply with the same force when the air em- 

 ployed for inflation is heated to 1 20 Fahr. ; then even fifteen minutes after 

 death, if the inflation be sustained, the heart is found contracting as the 

 chest is laid open, the action really being sustained by the diffusion of heat 

 from the lungs to the heart ; but the action excited is insufficient to produce 

 a pulmonic current. 



Effects of other gases used in artificial respiration. The experiments 

 were further modified by using for insufflation other gases in place of com- 

 mon air. Oxygen was thus used, oxyhydrogen, ozone, and air containing 

 0'20 per cent, of chlorine. With two exceptions, the same observations 

 are applicable to these experiments as were made in reference to those with 

 common air. As a rule, the gases possessed no action on the heart to 

 restore the pulmonic current when the natural action had been arrested. 

 The exceptions were, that when the action of the heart was still feebly pro- 

 ceeding, respiration not being suspended, the air containing chlorine or 

 ozone produced a quicker restoration, the ozone being much the less objec- 

 tionable in regard to its after-effects. 



Artificial respiration by electro-galvanic action. The experiments on 

 artificial respiration were finally modified by using the electro-galvanic cur- 

 rent to excite the muscles of respiration so soon as natural respiration and 

 circulation had ceased. By inserting a fine needle, insulated except at the 

 point, into the larynx of an animal, and the other needle into the diaphragm, 

 and by regulating the shock by means of a metronome, so that a given num- 

 ber of shocks representing the respirations of the animal are administered, 

 the most perfect appearance of natural respiration may be sustained for so 

 long, in some cases, as seven minutes ; and the phenomena are often re- 

 markable, and to the inexperienced deceptive. Thus, owing to the action 

 on the vocal apparatus, a rabbit will scream as loudly as in life ; and, lying 

 breathing and screaming, might well be considered to be alive. But all the 

 while the heart is at rest, if it have once rested, and on opening the chest 

 the lungs are found bloodless. 



