284 



Dr. Herbert Davies on the Ai'eas of the 



[Mar. 17, 



the healthy heart. Further more, I have proved, from my own measure- 

 ments, that the same law probably regulates the areas of the orifices in 

 animals generally ; and I have cited several examples in corroboration of 

 the statement. From the existence of this law, it is clear that if the areas 

 of any three healthy orifices be known, the area of the fourth can be de- 

 termined by calculation. 



I have then drawn attention to the curious and important fact which 

 appears to be almost general in animals, that 



T 



=1*3 to 1*4, nearly ; 



and 



P 



g =1'3 to 1*4, nearly; 



consequently that the dimensions of the openings of one side of the heart 

 being given, the areas of the corresponding orifices on the other side of the 

 organ may be obtained by arithmetical process. 



Having shown from measurements that the orifices arranged in the order 

 of their magnitude are as follows, 



1. Tricuspid, 



2. Mitral, 



3. Pulmonic, 



4. Aortic, 



I have sought to determine the reasons for this arrangement, to which 

 however, I shall not again refer. 



I propose on some future occasion to show how widely this "laic of the 

 orifices" which I have discovered is applicable to the heart in its diseased 

 state, and how it serves to explain many important and interesting points 

 Telative to the organ. I shall conclude with citing a few instances in which 

 its application throws some light on the effects of pulmonary disease upcii 

 the areas of the orifices. 



I. Phthisis (Dr. Peacock). 



Circumference. Area. 



Tricuspid 51 lines. ' 207 square lines. 



Pulmonic 39 121 



Mitral IS 183 



Aortic 36 I 103 



T _ 207, lo 

 P 121 

 Difference of the ratios = *04 



