102 PHYSIOLOGY AND HEALTH. 



branches to the brain within, and to the scalp and the parts 

 of the face without the skull. The subclavian veins (Fig. 

 XII. c,e) also pass off from the upper great veins. They go 

 through the arm-pit, and send numberless branches to the 

 arms and hands. The great abdominal cava sends branches 

 to the stomach, liver, alimentary canal, kidneys, &c., and 

 finally it is divided (Fig. XII. *, i) into two great veins, which 

 with their branches reach all the parts of the lower limbs 

 and feet, (Fig. XIII. h, h.) 



218. All these veins, like the arteries, are divided and 

 multiplied into branches almost infinitely small and numer- 

 ous, and thus they reach every part of the animal body, 

 (Fig. XIII.) 



219. The arteries are said to begin at the heart with one 

 large trunk, the aorta, (Fig. XL &,) and to end in all the near 

 and the remote parts of the body in almost infinite numbers 

 of minute tubes. The veins, on the contrary, are said to 

 begin in the flesh of all the parts of the body, with tubes 

 almost infinitely small and numerous, similar to the termi- 

 nating arteries, and end in one large trunk, the vena cava, 

 at the heart, (Fig. XIII.) These trunks meet at the heart 

 with their large trunks, and again they nearly meet through- 

 out the whole body with their minute extremities. 



220. The capillary system of blood-vessels is placed be- 

 tween the minute extremities of the 'arteries and the minute 

 ends of the veins. They are called capillaries from their 

 hair-like minuteness. They are even smaller than this, for 

 they cannot be seen by the eye. They are spread in every 

 part and every organ of the body. They form the connect- 

 ing link between the arteries and the veins, and carry the 

 blood from one to the other. 



221. The system of the general circulation of the blood if 

 thus composed of the heart, the arteries, the capillaries, and 

 the veins. The blood flows out from the ventricle on the left 

 side of the heart into the aorta. It passes through this large 

 artery into the large branches, and thence into the smaller 

 branches, and then through the minute branches into the 



