258 



ELEMENTS OF GENERAL SCIENCE 



contact with the cells of the body. The capillaries unite and 

 form the veins which finally, as large veins, lead back to the 

 heart. So rapid is the movement of blood that it is accurately 

 estimated that a given particle may leave the heart, make its 



- lung 



pulmonary vein 

 left auricle 



left ventricle 



aorta 



digestive tube \ 



pulmonary artery 

 lymph vein 



right auricle 

 right ventricle 

 caval vein 



'/- ..liver 



FIG. 124. Circulation of the blood 

 Diagrammatic representation of the circulation. After Colton 



round to one of the more distant parts of the body, and return 

 to the heart within half a minute. 



283. The heart as a force pump. The heart consists of four 

 sections, or chambers (two auricles and two ventricles), one 

 auricle and one ventricle on each side of the heart, and they 



