CHAPTER VII 



DIGESTION 



Mot/fh 



HMKr 



body. (From Mivart, by Gun- 



nison.) 



64. Review. We have 

 learned that each cell of the 

 human body must have foods 

 to keep it repaired and to 

 give it heat and energy. The 

 materials which the cells can 

 use are proteids, carbohy- 

 drates, fats, salts, water, and 

 oxygen. We have seen that 

 oxygen enters the blood 

 through the lungs and that it 

 is then ready to be carried to 

 all the tissues of the body. 

 We must now learn how water 

 and solid foods get into the 

 blood. The oxygen of the 

 air enters the blood without 

 being changed in any way, 

 for the oxygen in the blood 

 is just like the oxygen in the 

 atmosphere. The water also 

 mixes with the blood, un- 

 72 



