156 LIVING PLANTS 



shrub in a conservatory after removal from 

 its native forest. 



The full significance and real causes of the 

 phenomena attendant upon the fall of leaves 

 in autumn may only be comprehended, when 

 the uses subserved by the leaf, and the forms 

 of activity carried on underneath its surfaces 

 are recalled. 

 All the summer long the green surfaces have 

 Activity been lifted to the sunlight and by the magic 



of leaf Qf j^^g potent touch have taken in carbon 



dioxide from the air and combined it with 

 water in such manner as to form highly plas- 

 tic substances, which flowing steadily to dis- 

 tant portions of the plant have by the subtle 

 alchem3^ of protoplasm become converted into 

 wood, fiber, and cork, hard, firm and light 

 as such things only may be. 



The scene of activity in the leaf is laid in the 

 columnar and variously distorted cells con- 

 taining the green color bodies (chloroplasts) 

 and these cells are rich in protoplasm, albu- 

 minoids and sugar. A steady stream of wa- 

 ter is sucked up by the minute hairs on 

 the rootlets, and containing mineral salts 

 in solution, has poured upward into these cells 

 during the entire season. A small amount of 

 the water has been used in combination with 

 carbon dioxide in forming food, but by far the 

 greater proportion has been evaporated 



