FIG. 5. PINE TKEES ON MOUNTAIN SIDE. 



divide into two sets, one of which passes upwards towards 

 the light, the other passes downwards into the earth ; these 

 last (which pass downwards) form a fibre called the 

 "radicle" (fig. 6), those which pass upwards form also a 

 stalk or fibre called the " plumule," which 

 carries up with it a part of the seed called 

 the "cotyledon," which (like a leaf) has 

 the power of decomposing the carbonic 

 acid of the air and fixing its carbon in the 

 form of wood. This begins as soon as the 

 cotyledon has reached the light, and thus 

 the formation of fibres of woody matter 

 takes place, which fibres descend from the 

 cotyledon to the radicle. Meanwhile the 

 formation of other cells of the plumule 

 takes place, until the first leaf is formed, 

 when other fibres of wood are sent down, 

 and so on for every leaf, so that the number of woody 



PIG. 6. SEED BE- 

 GINNING TO GROW 



