CHAPTER XII. 

 NUTRITION. 



Ledger Account of the Body and its Organs. Through 

 the digestive tube and lungs the body receives additions, 

 and there is a corresponding loss through the lungs, skin, 

 kidneys, and intestines. So a ledger account might be 

 kept with the body, and it should balance in the long run, 

 since in adult life the weight remains practically constant. 



So we might take a single organ, say the liver, and 

 balance its accounts. It receives a large amount of blood. 

 To offset what it takes from the blood, it gives to the 

 intestines a large quantity of bile, and to the blood it gives 

 glycogen. 



It is especially interesting to note the losses and gains 

 of the blood as it passes through the various organs of the 

 body. A river, flowing past one State after another, will 

 take some of the soil of each and deposit some of its 

 muddy particles on the banks of each State. Of course, 

 the blood is unlike the river, in that it empties into itself ; 

 i.e. it is truly a circulation. The blood takes something 

 from, and gives something to, each organ as it flows 

 through it. From the intestine the blood gets the chief 

 part of its new material in the newly digested food. To 

 the muscles the blood gives nutritive material and oxygen, 

 and receives water, carbon dioxid, and other waste matters. 

 The account would be similar with the brain. In the skin 

 and the kidneys the blood has great losses and little gains. 



