COMPOSITION OF PLANTS AND ANIMALS 263 



Carbohydrates in the animal body are but contained in it, 

 not a part of it, and so this substance cannot be considered a 

 constituent of animal flesh. However, carbohydrates exist 

 in the body in two forms; one, glycogen, similar to starch 

 in composition, found in the liver and muscles; and the 

 other lactose, or the sugar of milk, found in milk. Dex- 

 trose is also found to a slight extent in the blood and tissues. 



Comparing plants and animals, we see that the plant 

 obtains its food from the air and from the mineral matter in 

 the soil, from which it develops a form made up of cells that 

 are largely carbohydrates. The farm animal obtains its 

 nutriment from the plant, from which is created a body form, 

 also composed of cells, but in this case, of nitrogenous mate- 

 rial. During the day the plant sucks in carbon dioxide from 

 the air through its leaves, and holds the carbon, and gives 

 off the oxygen. The animal, on the contrary, draws the air 

 into the lungs, uses the oxygen from it, and then breathes 

 out carbon dioxide. Thus we see that these two great 

 groups of living matter, the plants and animals, are of vital 

 importance to each other, and have much in common. 

 Without the plant or its products the animal could not live; 

 while by feeding on it, the beast converts the vegetable sub- 

 stance into a yet more concentrated and more valuable 

 material. 



REAL FOUNDATION QUESTIONS 



1. Name ten elements, tell where they occur and how taken up 

 by plants. 



2. How abundant and useful is water in the plant? 



3. Discuss protein and its occurrence. 



4. What two kinds of carbohydrates are there? Illustrate. 



5. Where in the plant is the fat most abundant? 



6. What is a concentrate? Give three examples. 



7. How much water is found in the animal body? 



