VOL. IV.] PHILOSOPHICAL TRANSACTIONS, 331 



SO ; as also why the oone in a human heart bends much more to the left side 

 than in brutes : Then showing that arteries have their rise from the heart, but 

 veins terminate in it, and how and by what vessels the heart is nourished by 

 the alimentary juice : treating also of the vessels of the heart, its nerves, and 

 the various influx of the animal spirits through the nerves into the heart, ac- 

 cording to the various shapes of animals, together with the cause thereof: 

 Proving further, that the substance of the heart is perfectly muscular, and in 

 perfection surpassing all other muscles of the body (where he expatiates into re- 

 markable observations concerning muscles in general;) then descending to a 

 minute explication of the parts of the heart, and there particularly showing 

 the mechanical contrivance of the heart for its systole and diastole, together 

 with an accurate description of the foramen ovale and its use in the foetus, and 

 the closing up of the same in animals born. 



In chap. 2 he treats of the motion and office of the heart ; where, as he ad- 

 mits not of any ferment or ebullition of the blood in the heart (which he affirms 

 would be an obstacle to its systole, as it is needless to the diastole,) so he asserts 

 that the motion of the heart depends not from such an ebullition (which he 

 proves by experiments, and vindicates from objections;) but that the genuine 

 and immediate instruments of the heart's motion are its fibres, nerves, and 

 spirits flowing through them, the action of the heart being altogether conform- 

 able to that of other muscles : where he takes occasion to make it out, that the 

 motion of muscles is not caused by their being inflated, nor by any explosion 

 of the spirits passing through them, but after the manner as two men, taking 

 one another by their hands, draw themselves close together into mutual embraces : 

 Whence he goes on to show, that the whole motion of the heart consists in- 

 deed in the systole, that of the diastole being only a motion of restitution. 

 Further, that there is a necessary commerce betwixt the heart and brain (the 

 cause of all sense and motion:) but that both ultimately depend upon the 

 stomach, as the constant purveyor and furnisher of matter for blood and spirits. 



In chap. 3 he teaches with what celerity all the blood passes through the 

 heart, and what difference there is between the venous blood and the arterial. 

 As to the former, he calculates, that all the blood passes through the body 1 3 

 times (not six as stated in the book itself by an error of the press) in one hour. 

 And concerning the latter, he is of opinion, that the purple and florid colour 

 of the blood in the arteries proceeds not from its accension in the heart (if there 

 be any such thing) but is derived altogether from the lungs, and the admixture 

 of the air with the blood there : which he proves by considerable experiments ; 

 refuting withal the opinion of those that attribute it to the comminution of the 

 blood in the lungs. 



T T 2 



