86 AGRICULTURE ON THE PACIFIC SLOPE 



Plants digest their food just as animals do. When 

 grain sprouts, some of the starch is changed to sugar. 

 This also happens when it is digested by the animal. 

 Taste some grains of wheat or barley which have 

 sprouted. Are they much sweeter than grains which 

 have merely, swollen over night in water? This is 

 because they have digested a part of their starch and 

 changed it to sugar. 



How is food used in building up the plant? All three 

 kinds of food (fats, sugar, protein) are needed for build- 

 ing up the plant. They move about in the stem to the 

 place where they are needed. When a potato begins 

 to sprout, the starch moves up into the stem and down 

 into the roots. 



Where does growth take place? Only at the tip of 

 root and stem (and at the tips of their branches) do we 

 find growth in length. (Grasses also grow at the 

 joints.) 



How much of the tip grows? Place some peas on 

 wet cloth in a dish and cover with glass. When the 

 roots are an inch long, put ink marks on them (a 

 quarter of an inch apart) by means of a splinter dipped 

 in India ink. Use a tape measure as a guide. The 

 marks will separate most where the growth is most 

 rapid. Mark the tips of some stems in the same way. 



What happens if the growing tip be injured? Remove 

 the tips from some of the roots and stems, and see what 

 happens. 



