MOTION OF THE HEART AND BLOOD 



the right side of the heart to the left. Both ventri- 

 cles equally have the same function of transferring 

 blood from the vena cava to the aorta through the 

 foramen ovale and the ductus arteriosusy and of 

 pumping it to the whole body, whence their struc- 

 tural equality. 



However, when the lungs are used and it is time 

 for the passages spoken of to be closed, then these 

 differences in the ventricles begin to appear, since 

 the right pumps only through the lungs, but the 

 left through the whole body. 



There are also so-called braces in the heart, many 

 fleshy and fibrous bands, which Aristotle calls 

 nerves (Be. Respirat. & De Part. Animal. ^ Lib. j). 

 They are stretched partly from place to place, and 

 partly in the walls and septum, where they form 

 little pits. Little muscles are concealed in these 

 furrows which are added to assist in a more power- 

 ful contraction of the heart and a more vigorous 

 expulsion of blood. ^ Like the clever and elaborate 

 arrangement of ropes on a ship, they help the heart 

 to contract in every direction, driving blood more 

 fully and forcibly from the ventricles. 



It may be shown, however, that some animals 

 have less than others, that in all animals with them, 

 they are more numerous and stronger in the left 

 than in the right ventricle, and in some animals where 



* T\vt%z papillary muscles, elongated into the chordae tendinae which 

 extend to the valves, seem to aid in closing the valves more exactly. 

 See Note 5, Chapter II. 



[119] 



