MAMMALIA 



287 



the living animal. The two vocal cords may be seen by 

 cutting the larynx lengthwise. They are flat ligamentous 

 folds on either side 

 of the larynx. 



The vessels re- 

 maining full of 

 blood are the veins. 

 The arteries are of 

 a lighter color, and 

 contain little or no 

 blood. The main 

 vein of the trunk 

 is the vena cava, 

 which opens into 

 the upper right 

 cavity of the heart, 

 called the right 

 auricle. From here 

 the blood passes 

 to the right lower 

 cavity, termed the 

 right ventricle, 

 which by the con- 

 traction of its 

 strong muscular 

 walls forces the 

 blood through the 

 pulmonary artery 

 to the lungs, to exchange the carbon dioxide, a waste 

 substance collected from all parts of the body, for 

 oxygen. The blood is returned from the lungs bysev- 



FIG. 324. Cat's brain viewed from above, a, &, c, 

 convolutions of the cerebrum ; ce, and v, cerebel- 

 lum ; md, medulla oblongata ; n, stump of the 

 nerve supplying the shoulder region ; sp, spinal 

 cord ; ad, body of nerve cells forming the gray 

 matter ; ac, processes of nerve cells forming white 

 matter. Three fourths natural size. From Davi- 

 son's " Mammalian Anatomy." 



