188 THE HUMAN HEART. 



scurely; however, the main guidance is, that the blood consists of 

 an orderly involution of the elements of the bodily organs : this 

 will give light upon what would otherwise be dark. We now recur 

 for a few moments to the coronary vessels, or to the circulation in 

 the walls of the heart. 



It is a curious fact that nearly all the old anatomists, and some 

 also of the moderns, have suspected a puzzle in these coronary ves- 

 sels. They come from the aorta and run backwards to the heart. In 

 a certain proportion of cases estimated at 5 in 20, one or more of their 

 orifices lies behind the semilunar valves, and such orifices it is clear 

 cannot receive the stream propelled from the heart, because it lays 

 down the valve flat upon them, and effectually closes them. As 

 therefore nature's law must be constant, it was argued, that what 

 holds of one orifice must hold of all ; and that the blood runs back into 

 the coronaries from the aorta when the heart's contraction ceases. 

 This was Boerhaave's opinion. Morgagni, a more practical anato- 

 mist, was more cautious, and requested others to decide the too diffi- 

 cult problem. Another view was now propounded by the celebrated 

 Swedenborg. He argued that the raising up of the semilunar valves 

 during the contraction of the heart, when the blood is expelled into 

 the aorta, precludes its passage then into the coronaries; and that 

 the stretching of the coronaries, and their pressure by the full aorta, 

 contributes to the same preclusion. Moreover, that to suppose the 

 heart supplied with blood by regurgitation from the aorta, would be 

 to ascribe to the latter a new action different from what it exerts 

 upon the other blood-vessels; nay to claim for it, after the discharge 

 of its functions, a stronger, inverted and retrograde action upon a 

 body the most muscular of any. These considerations led him to 

 infer, that the coronary arteries do not arise from, but terminate in 

 the aorta; that they are veins relatively to the heart, although run- 

 ning into the beginning of the arteries of the body. The doctrine 

 in brief is this : — that the heart as the head of the vessels and the 

 fountain of the blood, itself requires the firstling blood for the exer- 

 cise of its noble offices, and cannot hold its life by tenure from one 

 of its own arteries, which would be to invert all ideas of the order 

 of nature. The heart is already full of blood, and if fluids, or fluid 

 persons, like solid persons, move with greater velocity in proportion 



