CIRCULATION OF THE BLOOD 95 



regard to the pulse of the heart and arteries, viz., the 

 passage of the blood from the veins to the arteries, and its 

 distribution to the whole of the body by means of these 

 vessels. 



CHAPTER VI 



OF THE COURSE BY WHICH THE BLOOD is CARRIED FROM THE 

 VENA CAVA INTO THE ARTERIES, OR FROM THE RIGHT 

 INTO THE LEFT VENTRICLE OF THE HEART 



SINCE the intimate connexion of the heart with the lungs, 

 which is apparent in the human subject, has been the prob- 

 able cause of the errors that have been committed on this 

 point, they plainly do amiss who, pretending to speak of the 

 parts of animals generally, as anatomists for the most part 

 do, confine their researches to the human body alone, and 

 that when it is dead. They obviously do not act otherwise 

 than he who, having studied the forms of a single common- 

 wealth, should set about the composition of a general system 

 of polity; or who, having taken cognizance of the nature of 

 a single fiefd, should imagine that he had mastered the 

 science of agriculture; or who, upon the ground of one 

 particular proposition, should proceed to draw general con- 

 clusions. 



Had anatomists only been as conversant with the dissec- 

 tion of the lower animals as they are with that of the human 

 body, the matters that have hitherto kept them in a per- 

 plexity of doubt would, in my opinion, have met them freed 

 from every kind of difficulty. 



And first, in fishes, in which the heart consists of but a 

 single ventricle, being devoid of lungs, the thing is sufficient- 

 ly manifest. Here the sac, which is situated at the base of 

 the heart, and is the part analogous to the auricle in man, 

 plainly forces the blood into the heart, and the heart, in its 

 turn, conspicuously transmits it by a pipe or artery, or 

 vessel analogous to an artery ; these are facts which are con- 

 firmed by simple ocular inspection, as well as by a division 

 of the vessel, when the blood is seen to be projected by each 

 pulsation of the heart. 



The same thing is also not difficult of demonstration in 



