530 INDEPENDENT PULSATION OF PULMONARY VEINS, ETC, 



cases in which we have seen it to those in which we have not 

 seen it is very small. On looking through several modern text- 

 books of physiology, we have failed to find any mention of the 

 rhythmical contractile power of the pulmonary veins and^vena 

 cava ; but the earlier anatomists were well acquainted with it, 

 and Haller* states that he has seen the pulmonary veins con- 

 tinue to pulsate for two hours, and that others had seen the 

 vena cava pulsate for three hours while all motion in the other 

 cavities of the heart had already ceased. Johannes Miillerf 

 has also observed contractions of the vena cava and pulmonary 

 veins; and in young animals the contractions of the pulmonary 

 veins extend as far as they can be followed into the lungs. 



The importance of contraction of the vena cava and pul- 

 monary veins in preventing reflux of blood into them during the 

 contraction of the auricle, under circumstances when any 

 hindrance is opposed to the free flow of its contents into the 

 ventricle, is self-evident. Indeed Haller^ says that it was sup- 

 posed to exist by Senac, although he had not seen it. Especially 

 in cases of valvular disease of the heart is it likely to be of 

 great service ; and we think it advisable to bring again before 

 the notice of physiologists and physicians this power of the 

 veins, which, although so long known, appears of late years to 

 have been overlooked. 



* Elementa Physiologia, 1757, torn, i, pp. 410 and 399 ; and Memolres sur la 

 Nature sensible et irritable des parties du corps animal, 1756, torn, iv, p. 4. 

 f Miiller's Phiialo^ogy, translated bj Balv, 2nd ed., vol. 1, p. 1813. 

 ; Op. ciY., p. 410. 



