184 THE HUMAN BODY. 



pints of blood. In blood going to the lungs the main gas 

 is carbon dioxide (or carbonic acid), which is a waste product 

 of all the organs of the body. In blood coming from the 

 lungs the most abundant gas is oxygen. 



Summary. "Blood, then, is a very wonderful fluid: 

 wonderful for being made up of colored corpuscles and 

 colorless fluid, wonderful for its fibrin and power of clot- 

 ting, wonderful for the many substances, for the proteids, 

 for the ashes or minerals, for the rest of the things which 

 are locked up in the corpuscles and in the serum. 



" But you will not wonder at it when you come to see that 

 the blood is the great circulating market of the body, in 

 which all the things, that are wanted by all parts, by the 

 muscles, by the brain, by the skin, by the lungs, liver, and 

 kidneys, are bought and sold. What the muscle wants it 

 buys from the blood; what it has done with it sells back to 

 the blood; and so with every other organ and part. As 

 long as life lasts this buying and selling is forever going on, 

 and this is why the blood is forever on the move, sweeping 

 restlessly from place to place, bringing to each part the 

 things it wants, and carrying away those with which it has 

 done. When the blood ceases to move, the market is blocked, 

 the buying and selling cease, and all the organs die, starved 

 for the lack of the things which they want, choked by the 

 abundance of things for which they have no longer any 

 need." Foster. 



Hygienic Remarks. The blood flowing from any organ 

 will have lost or gained, or gained some things and lost 



What is the most abundant gas in blood going to the lungs? 

 What in that leaving those organs? 



Why may blood be justly called a wonderful fluid? Why is its 

 complexity not astonishing? Why is the blood always kept in move- 

 ment during life? What happens when the blood ceases to move? 



