ON THE MOTIONS AND SOUNDS OF THE HEART. 281 



arise from the septum very near the base, proceed from its sur- 

 face to the margin of the valve without the intervention of any 

 papillary muscle. 



This method of arrangement evidently depends upon the 

 general law of muscular contraction, according to which the 

 shortening of a fibre bears a definite ratio to its length in the 

 uncontracted state. The parts of the ventricle most remote 

 from the base receive the longest fibres, and accordingly make 

 the greatest degree of approach to it during their period of 

 contraction . 



§ II. — ^The Committee have repeated many of their former ex- 

 periments with regard both to the motions and sounds of the 

 heart, and have derived from them a confirmation of the views 

 detailed in their last Report. In order to elucidate the cause of 

 the sounds of the heart the following new experiments have 

 been performed. 



Experiment 1. — In a calf, pi'epared in the manner described 

 in the former Report, the thorax was opened, and the apex of the 

 heart cut off, so that the blood, during the contraction of the 

 ventricles, flowed into the chest, instead of passing into the 

 large arteries. An ear-tube being applied to the body of the 

 ventricles, one sound only was heard, resembling the first sound 

 of the heart, and coinciding with the ventricular systole. When 

 the blood had ceased to flow, a finger was inserted into the left 

 ventricle, by which it was firmly grasped at each contraction, 

 and the ear-tube being again applied to the surface, a sound, 

 which may be described as a dull thump, was heard simultane- 

 ously with the grasp of the finger by the ventricle. 

 , JExperimetit 2. — A stop-cock, communicating at one end with 

 a large bladder full of water, was inserted into the right auricle 

 of a human heart, and secured by a ligature. A glass tube, 2f 

 feet long, and ^ inch in bore, v/as tied into the pulmonary artery, 

 one inch above the semilunar valves. The bladder pressed upon 

 so as to fill the right ventricle, which was then compressed at 

 intervals by the hand, and thus the fluid was sent into the tube 

 by jerks, in imitation of the natural action of the heart. An ear- 

 tube being applied to the surface of the heart, two sounds were 

 heard, one prolonged, the other abrupt, very closely resembling 

 the natural sounds of the beating heart. The former sound was 

 heard during the contraction of the hand, the latter immediately 

 upon its relaxation. During the first sound the fluid ascended 

 in the tube, and descended a little when the second sound was 

 heard. The tube was now taken out of the artery ; the semi- 

 lunar valves were completely removed, and the tube was rein- 

 serted and fixed as before. The alternate compression of the 



