190 THE MOTION OF THE BLOOD. 



blood which they receive b , and that the auricles are of more 

 importance than the ventricles, mentions, among other examples 

 of diseased heart, one in which both ventricles were as completely 

 ossified as the cranium, except about a cubic inch at the apex, 

 and in which there had been no palpitation or pain in the heart. 

 As bony ventricles could not contract, nor easily be moved, pal- 

 pitation could not readily have occurred, and pain rarely attends 

 the ossification of any part. That the circulation was deranged 

 is proved by the woman having experienced great dyspnoea, 

 expectoration, and dropsy. The auricles were healthy, and 

 thicker than usual, and had evidently performed the duty of the 

 ventricles, through which, as an unchanging reservoir between 

 the auricles and the pulmonary artery and aorta, the auricles 

 drove the blood. The invariable languor of circulation in cases 

 where the action of the heart is languid, proves the power of the 

 heart in the circulation. 



On the other hand, the large arteries of the extremities are con- 

 tinually found ossified, though not obstructed, without any apparent 

 deficiency of circulation. I have seen long tracts of vessels in the 

 lower extremities ossified, where no such circumstance had been 

 suspected. Mr. Burns himself mentions an instance " of the arte- 

 ries of the head, pelvis, legs, and arms, being almost entirely ossi- 

 fied ," the heart and aorta being healthy; and yet the man clearly 

 died of diseased liver induced by hard drinking, hot climate, &c. 



The ventricles are certainly of more importance than the 

 auricles, because these are absent in many animals, and are only 

 reservoirs to supply the ventricles, when the extremities of the 

 great veins at the heart are not of very ample dimensions. d 



" It remains for us now to examine the aid given to the re- 

 turning blood by the veins, their radicles not being taken into 

 the account. We should conclude at first sight that they have far 

 less active power e than the rest of the sanguiferous system, and 



b 1. c. p. 120. c 1. c. p. 124. sq. d J. Hunter, 1. c. p. 138. 



e " What is commonly, but improperly, called the venous pulse, observable on 

 opening living animals, and in some morbid affections, and also under a violent 

 effort, does not correspond with the action of the heart, but with respiration ; 

 since, if an expiration is unusually deep and lengthened, and the reflux of the 

 blood to the lungs thus impeded, the jugular vein swells as far as the brain, the 

 subclavian as far as the basilic, and the inferior cava as far as the crural." But 

 there is also in some diseases of the heart a pulse of the lower portion of the 

 external jugulars, synchronous with the systole of the ventricles, and dependent, as 

 already explained, on the interrupted progress of the blood to the ventricles during 

 their contraction. A vein may pulsate from its proximity to an artery. 



