Work of the Heart 145 



ing called the right and left auricles, and the two 

 lower the right and left ventricles. The right auricle 

 is above the right ventricle and is separated from it 

 by a valve, and the same is true of the left auricle 

 and ventricle. Out of the left ventricle the blood is 

 pumped into the arteries and after reaching the arte- 

 rial capillaries throughout the entire body, it passes 

 from these into the smallest divisions of the veins and 

 comes back to the heart along the venous system, en- f 

 tering the right auricle. It is then carried to the 

 lungs by way of the right ventricle and is returned to 

 the left auricle to be sent to the left ventricle, and 

 from there to again start on its journey through the 

 body. The principal facts pertaining to the blood and 

 its circulation have been reviewed in this simple man- 

 ner as an aid to the discussing of other considerations 

 somewhat pertinent to our subject. 



The nutrients, as prepared for use by digestion, 

 enter the blood on its return flow to the heart, com- 

 ing into the venous cavity by way of the hepatic 

 (liver) vein and the thoracic duct as previously de- 

 scribed. When, therefore, the right side of the heart 

 is reached, a new accession of food material is on its 

 way to sustain the various functions of nutrition. 



We are more interested in the object of blood cir- 

 culation than we are in its mechanism. Somehow the 

 digested food disappears into these constantly moving 

 blood currents, and the only evidence of its effect 

 which comes to us from ordinary observation is the 

 warmth, motion and perhaps growth of the animal that 

 is nourished. 



