PHYSIOLOGICAL ANATOMY OF THE HEAET. 179 



made by calculating the amount of liquid displaced by the 

 moulds of the different cavities. Care was taken to make 

 the injection in animals before cadaveric rigidity set in, or 

 after it had passed away in the human subject. The com- 

 parative results obtained by these observers are the most 

 interesting, for the cavities were undoubtedly distended by 

 the injection to their extreme capacity, and contained more 

 than they ever do during life. They found the capacity of 

 the right auricle from T V to ^ greater than that of the left. 

 The capacity of the right ventricle was from T 1 to ^ greater 

 than that of the left, but more frequently there was less dis- 

 parity between the two ventricles than between the auricles. 

 The capacit} 7 of each ventricle exceeded that of the corre- 

 sponding auricle by from \ to -J. Nine times out of ten, this 

 predominance of the ventricle was more marked on the left 

 side. The absolute capacity of the left ventricle, according 

 to these observations, is from 143 to 212 cubic centimeters, 

 which is about 4*8 to 7 ounces. This is much greater than 

 most estimates, which place the capacity of the various cavi- 

 ties, moderately distended, at about 2 ounces. The estimates 

 of Yolkmann and Valentin are about equal to those we have 

 cited. 



In spite of the disparity in the extreme capacity of the 

 various cavities, the quantity of blood which enters the cav- 

 ities is necessarily equal to that which is expelled. This is given 

 in the "Cyclopaedia of Anatomy and Physiology" (vol. ii., 

 p. 585) as a little more than two ounces. There are no means 

 of estimating with exactness the quantity of blood discharged 

 with each ventricular contraction ; and we find the question 

 rather avoided in works on physiology. All we can say is, 

 that from observation on the heart during its action, it never 

 seems to contain much more than half the quantity in all its' 

 cavities that it does when fully distended by injection ; but 

 it is the right cavities which are most dilatable, and prob- 

 ably the ordinary quantity of blood in the left ventricle is 

 within one-fifth or one-sixth of its extreme capacity. 



