CHAPTER XI 



FOODS IN THE TISSUES 



105. Review. We have traced the foods and oxygen 

 into the blood and have studied the organs by which 

 the blood is distributed to all parts of the body. As yet 

 the foods have been of no value, in fact they have been 

 an expense at every step without yielding any return. 

 Energy has been used in cooking and preparing foods 

 for the table, and then mastication, digestion, and 

 absorption have cost much labor. Then, by the hard 

 work of the heart, they are forced through the arteries, 

 capillaries, and veins. But while the blood passes 

 through the thin-walled capillaries much of the oxygen, 

 albumin, sugar, fats, water, and salt exudes through the 

 walls of the capillaries and forms part of the lymph. 

 Now the foods are within reach of the cells ; they are 

 soon to serve their real purpose. 



106. The Lymph. We have learned something about 

 the lymph in former chapters. It is quite like blood in 

 composition except that it contains no red corpuscles 

 because they cannot pass through the walls of the 

 capillaries. It is about ninety per cent water, and the 

 remainder consists of solids held in solution. The cells 

 select from the blood what they need for their own use, 



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