ON THK MOTIONS AND SOUNDS OK THE HEART. 268 



first sound is louder and fuller-toned, and accompanied by strong 

 impulse. They found also that fixll inspiration operated like 

 leaning to the right, or the supine position, by diminishing 

 sound and impulse, while full expiration like leaning forwards, 

 or to the left side, rendered the sounds and impulse more di- 

 stinct, the former louder, the latter stronger and more dif- 

 fused. When the heart's action is excited by exertion they 

 found, as might be anticipated, the systolic sound and impulse 

 at their maximum of tone and force. Moderate exertion they 

 observed to increase the intensity of both sounds ; whereas sud- 

 den exertion, sufficiently violent greatly to accelerate the action 

 of the heart, they found impaired the distinctness of the second 

 sound, the first continuing loud, short, and with strong impulse. 



The indistinctness of the second soimd in rapid pulsation of 

 the heart, seemed to depend in part on its following so closely 

 on the loud first sound as to be masked by it. 



Experiment 2. — The Committee made experiments likewise 

 on muscular contraction in their o\vn persons, with a view to 

 ascertain how far that act is accompanied by sound. The mus- 

 cles operated on with the best effect were the buccinator and 

 masseter, the muscles of the neck and fore-arm, and of the pa- 

 rietes of the abdomen. In all those the flexible ear- tube, care- 

 fully applied so as to prevent friction, yielded sounds more or 

 less striking ; but the most striking results were obtained from 

 the last-mentioned parts. From the abdominal muscular con- 

 tractions, sounds of a " systolic " character (if the expression is 

 admissible) in all respects, and as loud or louder than those of 

 the heart, were with facility obtained : the sounds were excited 

 by sudden expiratory efforts made with force, and with the 

 mouth closed, and were obtained from various parts of the pa- 

 rietes. The sound of muscular contraction seems in the case 

 of the abdonunal muscles to be exaggerated by the hoUowness 

 of the subjacent parts. 



At the time the sound was heard the muscle under observa- 

 tion always felt to the finger tense and hard, but the loud sound 

 ceased at the moment that the fibres had attained their maxi- 

 mum of tightness and hardness, and was not renewed except by 

 a repetition of the contractile effort after pre^dous relaxation. 



Experiment 3. — Subject, a young ass poisoned with jvoorara 

 introduced into an incision in the flank. 



The animal died sixteen minutes after the introduction of the 

 woorara ; much blood was lost in opening the chest ; the heart 

 was acting at the moment of exposure, but not strongly. Its 

 action became more regular after inflation was made more re- 

 gularly. 



