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 probable 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 re- 

 searches to the human body alone, and that when it 

 is dead. They obviously act no 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 field, should imagine that he 

 had mastered the science of agriculture ; or who, upon 

 the ground of one particular proposition, should pro- 

 ceed to draw general conclusions. 



Had anatomists only been as conversant with the 

 dissection of the lower animals as they are with that of 

 the human body, the matters that have hitherto kept 

 them in a perplexity 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, they having no lungs, the thing 

 is sufficiently manifest. Here the sac, which is situ- 

 ated at the base of the heart, and is the part analogous 

 to the auricle in man, plainly throws the blood into the 

 heart, and the heart, in its turn, conspicuously transmits 



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