218 PHILOSOPHICAL TRANSACTIONS. [aNNO ! 705- 



The Explanation of the Figures. — Fig. 1 1 represents the left ventricle of the 

 heart opened, &c. aaa the inside of the aorta slit open to the left ventricle; 

 BB the bulbous trunk of the vena pulmonalis divided through, and pinned aside; 

 to show aaa the three semilunar valves of the aorta, which hinder the blood 

 from returning to the heart ; b a small stony substance at the conjunction of 

 two of the semilunar valves, expressed at the * below this figure: aa parts of 

 the two valves dried; b the petrifaction, as it appears in the dried valves; c part 

 of the lower trunk of the vena cava, cut off immediately above the liver ; ccc 

 the left auricle opened and pinned out ; dd the sides of the left ventricle divided 

 and drawn aside, to show its inside dd ee f f gg ; dd the mitral valves of the left 

 ventricle of the heart, or arteria pulmonica, divided and turned aside ; ee the 

 carneaB columnae, whence spring the tendons fastened to the valves, dd, ex- 

 pressed by df in fig. 13 ; ff a transverse cord or tendon, by which the columnae 

 carneae are drawn nearer each other in the systole, or contraction of the heart, 

 when the blood is expelled into the aorta ; by which the tendons expressed (f, 

 fig. 13 and 15, draw the mitral valve laterally ; by which means its orifice gc, in 

 the said figure, is not only closed to prevent the return of the blood by the vena 

 pulmonalis, but at the same time it opens a passage for the blood of the arteria 

 magna, by withdrawing the mitral valve d, fig. 12, from the orifice of the aorta 

 aaag; g© the internal surface of the left ventricle, where it is somewhat 

 smoother as it leads to the aorta; gg the trunk of the coronary vein divided 

 when filled with wax; hh the coronary artery in like manner divided ; i one of 

 the trunks of the vena pulmonalis ; kkk the three orifices of the trunks of the 

 vena pulmonalis, as they open into the bulbous trunk ; expressed at bb ; h the 

 cone of the heart. 



In fig. 12, A is part of the aorta next the heart; aaa the three semilunar 

 valves, as they appear next the heart in a natural state, when the heart is in 

 diastole, and the blood hindered by these valves from returning to its left ven- 

 tricle ; bb part of the basis of the heart cut off; ee the two columnae carnae 

 of the left ventricle ; d the mitral valve ; ff the tendons springing from the 

 carneae columnae, and inserted into the upper and middle parts of the valve, as 

 well as to its lower margin; which is better expressed in the following figure; 

 g the orifice of the aorta completely closed by the application of these three 

 valves to each other. 



Fig. 13 shows the same parts as in the preceding figure, as they appeared 

 when the valves of the aorta were petrified, excepting a, which represents a 

 part of one of the valves that was not covered with the petrifaction ; bbb the 

 petrifactions on the rest of the valves ; ^ a small petrifaction on the mitral 



