THE MOTION OF THE BLOOD. 1*75 



it occur at the same moment with their stroke r ; and the impos- 

 sibility of passage into the ventricle explains the fact. Indeed, 

 not only, according to my experience, does the swelling of the 

 jugulars occur after the moment assigned by these writers to the 

 contraction of the auricles, but, as, at the moment the auricles 

 lose their blood, the ventricles are relaxed or expanding, there 

 can be no reason for the blood moving at all backwards when the 

 auricles contract. 



The object of the appendix of each auricle usually contract- 

 ing later than the sinus, that is, just before the ventricle, if 

 it really does, is probably, by pouring its blood into the sinus 

 which has just parted with much of its own to the ventricle, and 

 by lessening the space for the blood streaming to the auricles 

 from the veins, to bring the distension of the ventricle, which is 

 already in diastole, to the highest pitch ; or, if the expansion of 

 the ventricle is spontaneous, to thus cause it to be supplied with 

 blood in proportion to its expansion. 



Many hypotheses have been invented to explain the two sounds; 

 and the periods of the action of the auricles and ventricles relative 

 to each other and to the arterial pulse been strangely misrepre- 

 sented. But Laennec was right in asserting that the first sound 

 occurs when the ventricles part with their blood, and the second 

 ivhen the auricles part with theirs ; for the first occurs when the 

 heart strikes against the ribs and the aorta receives a fresh quantity 

 of blood from the heart, and the second, when the ventricles expand 

 and the blood must rush from the auricles : the first is loudest 

 in the ventricular region, the second in the auricular : and, 

 when the appendices of the auricles were contracting with all 

 sorts of irregularity, with no relation to the contraction of the 

 ventricles in the ass, T heard, by means of the stethoscope, the 

 two usual sounds occur with the greatest regularity. We may 

 therefore presume that the first arises from the rush of blood 

 from the ventricles, and the second from the rush of blood from 

 the sinuses of the auricles. 



" The impulse imparted by the heart to the blood is com- 

 municated to the arteries, so that every systole of the heart is 

 very clearly manifested in those arteries which can be explored 

 by the fingers and exceed -J of an inch in the diameter of their 



r I have at this time a patient whose external jugulars are enormously dis- 

 tended, and immediately above the clavicles, the most frequent spot, their puls- 

 ation may be seen and felt exactly synchronous with the radial pulse. 



N 2 



