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CHAPTER IV. 



A SUGGESTIVE READING LESSON. 



SOME FEATURES OF PLANT GROWTH. 



James Atkinson, Ames, Iowa. 



With the exception of products of the sea the entire food supply 

 for mankind is derived from the plant world. Whether it be 

 breadstuffs or meats, they are alike the finished product of vege- 

 tation. Nature has made provision for the support of primitive 

 man, but as civilization advances the art of man is used to multi- 

 ply the products of vegetation, both in variety and quantity. It 

 matters not whether our lot be cast in a great metropolis or on the 

 prairie plains, our vital concern in the products of vegetation is 

 the same and should be sufficient to stimulate us to acquire a 

 knowledge of the habits of growing plants, and the characteristics 

 of some of the world's staple crops. 



ORGANS OF VEGETATrox:-If a Seed is placed in a soil under cer- 

 tain conditions of warmth and moisture, green leaves soon make 

 their appearance above the ground while roots develop and pene- 

 trate the soil. These, together with the stem, constitute the 

 organs of vegetation. It is our purpose to investigate some of 

 the problems connected with the development of these organs. 



COMPOSITION OF PLANTS. All plants are not alike in composition, 

 but in a general way they are alike in being composed of water 

 and dry matter. Nine-tenths of such crops as potatoes, turnips, 

 and beets are composed of water. 



To find out whether or not plants contain water, a simple ex- 

 periment may be tried. 



Pull about a pound of green grass, weigh it carefully, then place it in an 

 oven. Leave it there until it seems perfectly dry, then remove and weigh 

 again. The loss in weight represents the amount of water the plant con- 

 tains. 



WATER. From what source is this water obtained and of what 



value is it to a plant? As the roots penetrate the soil they con- 

 stantly come in contact with a certain amount of water. Some- 

 times this is present in sufiicient quantities to completely saturate 

 the soil, while at other times the soil may scarcely be damp. It 

 passes through the roots and stein and is evaporated from the sur- 

 face of the leaves. In its passage through the plant it carries 

 with it plant food from the soil, and also carries the food formed 

 within the plant to where it is required. 



Besides being a vehicle of food, it has other functions to per- 

 form. In the first place its passage from the cool soil into the 



