CHILDREN'S GARDENS 



til the water of the soil-film is saturated. The 

 amount of plant-food in solution increases with 

 the temperature and is moved from place to 

 place by capillary water. Root-hairs of plants 

 utilize portions of dissolved mineral matter and 

 cause solution to go on at a more rapid rate. 

 The process by which food-laden water enters 

 root-hairs, rises in the stem, and into the leaves 

 and sunshine above, is called osmosis. 



When two liquid substances are separated by 

 a membrane, through which these liquids can 

 pass, the greater flow is toward the denser solu- 

 tion. A cucumber put into fresh water will be- 

 come crisp, because the exchange of liquids is 

 more rapid toward the cell-sap ; put into strong 

 salt water the cell-sap flows more rapidly into 

 the dense salt water, and the cucumber shrivels. 

 A cooked prune or raisin becomes plump for the 

 same reason. If the water is consumed as plant- 

 food or lost by evaporation or transpiration, the 

 osmotic pressure at that point is diminished, and 

 the flow from adjoining cells makes good the 

 loss. Water acts as a medium through which 

 mineral salts in solution are carried to different 

 parts of the plants. The assimilated products 

 are transferred to be stored in seeds, leaves, 

 roots and stems, while the superfluous water 

 passes into the air by transpiration and evapo- 

 ration. 



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