HARVEY AND THE HEART 93 



Our interest in the lecture quickens as the learned 

 Fabricius goes on to explain the use of the heart. " Cut 

 it out of a living body and what happens ? " he asks. 

 That body dies and grows cold. That is a convincing 

 proof that the heart is the source of both life and heat. 

 Clearly it is the vat or retort in which the " vital spirits " 

 of life are brewed and mixed with blood. The M vital 

 spirits " endowed the tissue of the body with life, and hence 

 a great channel, the aorta, led out from the main chamber 

 of the heart — the left ventricle. From the aorta there 

 opened out other channels or arteries, passing to the 

 arms, to the head, neck, and brain, while the aorta itself, 

 after descending within the thorax and abdomen, ended by 

 dividing into the two great arteries of the lower extremities 

 (fig. 25). By means of these arteries the heart distributed 

 life and heat to all parts of the body. Anyone could 

 prove that what he taught was true by simply tying the 

 main artery going to a limb. Thereby the limb was cut 

 off from its source of heat and life ; it became cold and 

 mortified. Every part of the body was therefore supplied 

 with a double set of vessels : (1) veins which conveyed 

 nourishing blood, (2) arteries carrying blood which was 

 endowed with life and heat. 



The heart, however, could give out life and heat to 

 the tissues of the body only if it were supplied with two 

 things — air and blood. That both of these were richly 

 supplied to the heart all the world knew. Every breath 

 that was drawn was to furnish the heart with air. The air 

 was drawn down the wind-pipe or rough artery (trachea) 

 to reach the lungs ; there it was taken up by certain vessels 

 in the lungs — the pulmonary veins — and conveyed by them 

 to the left chambers of the heart, first to the left auricle 

 and then to the left ventricle, the chief brewing chamber. 

 It was therefore easy to understand why we breathed and 

 why there was a trachea and lungs. It was clear why a 

 man died when he choked ; the air could no more reach 

 the heart ; vital spirits could no longer be concocted, and 

 hence immediate death ensued. There again knowledge 

 seemed perfect ; no discovery remained to be made. 



