THE f I.ANT 37 



them germinate, they need three things, moisture and warmth 

 and air. Let us supply these. Put some cotton seed in a flower- 

 pot filled with fertile soil. Keep it moist and warm, and your 

 seeds will germinate and develop into plants. 



In the soil, however, you cannot watch the development as you 

 would like to do. For this purpose, let us use a glass. Fill it 

 with soil, and plant cotton seed next to the glass. Fasten paper 

 or cloth around the outside, to exclude the light ; keep the soil 

 moist, and the glass in a warm place. The seeds will germinate 

 more quickly if they are soaked twenty-four hours before they are 

 planted. 



How Plants Grow. As a seed absorbs moisture, it swells. 

 Then it puts forth a tiny shoot, the first root ; from the other end of 

 this, after a while, it puts forth the beginning of the stem. The first 

 tiny shoot turns downward into the soil, never by any chance making 

 a mistake and growing upward. The stem goes upward into the 

 air and sunlight as surely as the root goes downward into the soil 

 and darkness. 



We said that the store of nourishment in the seed enables the 

 plant to put forth its root and stem. But that store is soon ex- 

 hausted, and the little plant must get food for itself. This is, in 

 part, the work of the root. 



How Plants Feed. The cotton plant has what is called a tap- 

 root, a long, straight main root. From this grow branch roots, which 

 divide and subdivide into rootlets, from the ends of which grow 

 hundreds and thousands of root hairs. These are like tiny hands 

 reaching out for water and food. 



Plant Food from Soil. But what is plant food ? Why, it is 

 the elements of which you learned in the chapter about The Soil. 

 Some of these elements nitrogen, sulphur, phosphorus, potas- 

 sium, calcium, magnesium, and iron, in compounds which the 



