Heart and Blood 27 



in the bellies of the muscles of the body at large. To 

 all this, let it be added, that not only are the ventricles 

 contracted in virtue of the direction and condensation 

 of their walls, but farther, that those fibres, or bands, 

 styled nerves by Aristotle, which are so conspicuous in 

 the ventricles of the larger animals, and contain all the 

 straight fibres, (the parietes of the heart containing only 

 circular ones,) when they contract simultaneously, by 

 an admirable adjustment all the internal surfaces are 

 drawn together, as if with cords, and so is the charge of 

 blood expelled with force. 



Neither is it true, as vulgarly believed, that the heart 

 by any dilatation or motion of its own has the power of 

 drawing the blood into the ventricles ; for when it acts 

 and becomes tense, the blood is expelled ; when it 

 relaxes and sinks together it receives the blood in the 

 manner and wise which will by and by be explained. 



