ARTERIES, VEINS. 211 



removes the fluids which are poured out into them 

 these are called absorbents ; a fifth set covers 

 the surface of the body, the mouth, the linings of 

 other great cavities, and is always exuding or 

 secreting fluid to keep them moist these are call- 

 ed secretory vessels. How wonderful it is, that 

 we can run, jump, and perform other violent exer- 

 cises, without disturbing the action of these thou- 

 sands of delicate organs. 



The arteries are the vessels which convey blood 

 from the heart to all parts of the body. One great 

 artery arises directly from the heart. This is very 

 large. Before it has gone far, however, it begins 

 to divide, or branch, and, in its progress along the 

 body, it sends off divisions to all the parts which 

 it passes. 



When this has reached the lower part of the 

 back-bone, it divides itself into two large vessels, 

 one of which goes downwards to supply each of 

 the lower limbs. These branches, as they pass 

 along, keep ramifying, or dividing, till they are 

 so small, that we can no longer trace them. 



Every thread of muscle, and the coats of the 

 arteries themselves, are thus abundantly provided 

 with small vessels ; nay, so full are the muscles, 

 that their red colour is owing to blood vessels. 



The large arteries are very carefully protected 

 from injury, and generally lie buried deep amongst 

 the muscles. Were they to be cut, we should soon 

 bleed to death. There are some places, as the 

 wrist and the elbow, where they have to pass over 



