MOTION OF THE HEART AND BLOOD 



But to go on with our subject, on the function of 

 the auricles in filling the ventricles with blood, it may- 

 be observed that the thicker and denser the walls of 

 the heart itself, the more fibrous and muscular are 

 the auricles, and the reverse. In some animals the 

 auricle appears to be a bloody membranous sac, as in 

 fishes, where it is so delicate and ample that it seems 

 to float above the heart. In other fishes as the carp, 

 and barbel, in which this vesicle is a Httle more 

 fleshy, it bears a striking resemblance to lungs. 



In some men of heavier and huskier build, the 

 right auricle is so robust and so well braced inside by 

 bands and various connecting fibers that it approxi- 

 mates in strength the ventricle of other subjects. I 

 marvel that there is such variation in this in different 

 men. 



It is noteworthy that the auricles are dispropor- 

 tionately large in the fetus, because they are present 

 before the rest of the heart is made or can take up its 

 function, so that, as shown before, they assume the 

 duty of the whole heart. 



My observations previously referred to on the 

 development of the fetus, and which Aristotle con- 

 firms in regard to the egg, throw great light on this 

 matter. While the fetus is till soft like a worm, or, 

 as is said, in the milk," there is a single bloody spot, 

 or pulsating sac, as if a part of the umbilical vein 



" I can't trace the origin or significance of this expression. My 

 wretched Longhine edition, Bonn, 1697, rendered vermicules as ven- 

 tricules, and lacte as lucte\ 



I 125] 



