164 THE NATURE AND WORK OF PLANTS 



in the cocoanut, serves as a digesting 

 and absorbing organ. It develops as 

 a cylindrical mass, and its juices corrode 

 the hard cellulose of the seed which is 

 stored as food for the young plantlet. 

 The absorbing organ expands until it 

 consumes all of the cellulose, and finally 

 fills up the entire space inside the coats. 

 b. Sketch the development of the basal end 

 of the cotyledon. It elongates and 

 forces the embryo stem tipped with the 

 root downward through the soil. As it 

 does so it opens at one side and allows 

 the first green leaf of the plumule to 

 come out. Finally the root begins to 

 develop, and it continues the downward 

 course taken by the cotyledon. If the 

 seeds were in the dry soil in which 

 the plant grows, the root and cotyledon 

 would bore down more than a yard be- 

 fore any branches would be given off. 

 But in the pot cultures this is impossi- 

 ble and unnecessary, for the plant finds 

 sufiicient moisture near at hand. So far 

 as can be found from an examination of 



