136 INDEPENDENT PULSATION OF PULMONARY VEINS, ETC. 



pulsating in a cat killed by a blow on the head. We have 

 also seen pulsation in animals killed in other ways ; but the 

 proportion of 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 continue 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 contrac- 

 tions 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, Hallerj: 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 Memoires sur la 

 Nature sensible et irritable des parties du corpes animal, 1756, torn, iy, p. 4. 

 t Miiller's Physiology, translated by Baly, 2nd edit., vol. i, p. 182. 

 X Op. cit., p. 410. 



