THE MOTION OF THE BLOOD. 191 



that the return of their purple blood to the heart is chiefly 

 ascribable to the impetus a tergo of the arterial blood, and to 

 their valvular structure, which prevents any reflux. The efficacy 

 of the valves in this point of view, is shown by the distensions 

 and infarctions of the veins in the lower part of the abdomen, 

 which are found destitute of valves. f 



" The existence of vital powers in the venous trunks is pro- 

 bable g , from the example of the liver and placenta, and from 

 experiments instituted on living animals. We formerly men- 

 tioned the muscular layer in the extreme veins near the heart." 



In a young lady, whom I attended, before the days of ausculta- 

 tion, for chronic bronchitis accompanied by violent cough, and 

 who ultimately recovered, all the veins of the back of the hands 

 and fore-arms distinctly pulsated synchronously with the arteries. 

 Hunauld and Laennec each saw a similar case. h An universal 

 pulsation of the veins synchronous with that of the arteries, 

 occurred for some days twice in a young man who died of ce- 

 rebral disease, with constriction of the mouth of the aorta 1 ; once 

 in a middle-aged man with affections of the head and abdo- 

 men, who recovered '; once in a middle-aged man who died with 

 dropsy and palpitation k , and in a girl who died with symp- 

 toms of hydrocephalus. ' In a case of epidemic fever, the same 

 was observed by Weitbrecht for twenty-four hours m ; and he had 

 previously seen a similar case, but doubted his senses. Haller's 

 remark upon it is, " Ego quidem non intelligo."" 



In venesection at the bend of the arm, I have frequently seen 

 the jet regularly stronger at each pulsation of the heart ; and 

 J. Hunter mentions the same thing, and states it to be more 

 observable at the head or foot, saying, " The fact is, however, 

 that there is a pulsation in the veins. 



Yet ordinarily there is, speaking of the veins in general, iro 

 venous pulsation, and the stream in the veins, though caused 



f " G. E. Stahl, De vena portce porta malorum. Halae, 1698. 4to." 

 e ". Lister, De humoribus, p. 25." 

 h Laennec, 1. c. p. iii. s. ii. ch. ii. 

 * Journal Complimentaire, t. 21. June, 1825. 

 J Journal der Praktischen HeUkund. Sept. 1815. 

 k Archiv.ftir Medinische Erfahrung. July and August, 1822. 

 1 Dublin Hospital Reports, vol. iv. 

 111 1736. Haller's Disfmtationes, t. v. p. 407. 

 " El. Phys. t. ii. p. 356. 1. c. p. 186. sq. 



o 2 



