534 EFFECT OF VENOUS BLOOD ON THE HEART. 



thus divided, life continues, and respiration goes on, from half an hour to 

 ten hours ; but his arterial blood is in a state of great disoxygenation or 

 carbonation during this time. This fact is more remarkable because venous 

 blood, contained in a bladder exposed to the open air will become oxygenated 

 or decarbonated. 



It is also asserted in another Memoir, read to the National Institute by Dr. J. M. 

 Provencal ; that animals, in whom the eighth pair of nerves has been divided, 

 do not consume so much oxygen, or produce so much carbonic acid, by a 

 considerable degree, as they did before the division of these nerves ; and that 

 their temperature is considerably reduced.* 



The effect, that venous blood occasions death, when it is admitted into the left 

 ventricle of the heart, and the aorta, is truly important. Dr. Goodwin 

 explained it by suggesting that this blood was not sufficiently stimulating to 

 produce the necessary excitement of the heart ; but on this occasion one of his 

 friends proposed to him the following question : Why does venous blood affect 

 the left side of the heart in this injurious manner, when it appears to exert no 

 noxious effects whatever on the right side of that organ ? His reply may be 

 seen in a note at the 82d page of his Essay, in the first edition. Bichat has 

 offered a solution which completely resolves this difficulty, viz. " The effect of 

 venous blood upon the heart is produced by the presence of this blood in the 

 proper, or coronary arteries of that organ, and not in its great cavities." For 

 the animation of the heart, like that of the other parts of the body, depends 

 upon the state of the blood in the arteries which penetrate its texture.f And 

 while the heart acts, the blood of the coronary arteries will be the same with 

 that of the left ventricle. See Bichat's Researches, P. II. art. 6, $ 2. 



The French anatomists at one time entertained some peculiar opinions respecting 

 the course of the blood in the fostus, which have a particular relation to the 

 subject last mentioned. Winslow, who paid great attention to the valve of 

 Eustachius in the right auricle of the heart, was of opinion, that this valve 

 was calculated for some important purpose in the foetal economy.! Although 

 his hypothesis respecting its particular use has not been retained by his 

 countrymen, many of them have adopted his general sentiment ; and among 

 others Sabatier. That learned anatomist believed that this valve, in the 

 foetal state, serves to direct the blood of the inferior cava, after its arrival in the 

 right auricle through the foramen ovale into the left auricle ; while the blood of 

 the upper cava passes directly into the right ventricle. His opinion seems to be 

 supported to a certain degree 



1. By the direction in which the two columns of blood enter the auricles 

 from the two venae cavae. 



2. By the position of the Eustachian valve. 



3. By the foraman ovale, when its valve is complete ; as the passage 

 through it from the right to the left, is at that time oblique, and from below 

 upwards. 



* These Memoirs were republished in the Electic Repertory of Philadelphia for April and 

 October, 1811. 



t It is probable that the contents of the great cavities of the heart have no more effect 

 upon its animation than the contents of the stomach and bowels have upon the animation 

 of those organs. 



J See Memoirs of the Academy of Sciences for 1717 and 1725, 



