308 



MAMMALS 



lungs to be purified. The blood is returned from the lungs 

 through the pulmonary veins to the left auricle. From 



^ .„ here it flows into the left 



Capmanes , . , , -, ■ 



■ -^ ' ventricle whence it is ex- 



pelled through a system 

 of arteries to all parts of 

 the body (Fig. 204). 



Excretorysystem. — The 

 carbon dioxide and other 

 waste materials gathered 

 from the body by the 

 blood is exchanged in the 

 lungs for oxygen and ex- 

 pelled through the wind- 

 pipe. 



A pair of bean-shaped 

 kidneys attached to the 

 dorsal side of the abdo- 

 men gather the nitroge- 

 nous waste matters of the 

 body and discharge them 

 through the ureters into 

 the urinary bladder. 



Brain and spinal cord. 

 — The surface of the brain 

 is not greatly convoluted 



Fig. 204. -Circulation of a rabbit show- ^j^ ^ j ^ ^^^^^ 



mg the course of the blood. 1 he dark 

 vessels contain impure blood and the brain, thuS indicating a 



light vessels pure blood. ^^^ ^^^^^ ^f intelUgence. 



The brain consists of several distinct parts. In front is 

 the cerebrum, made up of two large hemispheres, on the 

 anterior extremities of which are the two club-shaped 



