16 THE PLANT. 



soil and weather, must be attributed to the great number 

 of plants which are able to continue for a shorter or 

 longer period at a low stage of developement. While the 

 one species of plants is developed above ground, producing 

 flowers and seeds, a second and third species gather 

 below the surface the conditions for a similar future 

 growth. The one vegetation seems to disappear, to make 

 room for another and a third, until for itself too the con- 

 ditions for a perfect developement recur. 



The woody plants grow and are developed in a manner 

 quite similar to the asparagus plant, with this difference, 

 however, that they do not lose their stem when the 

 period of their vegetation comes to an end. An oak- 

 saphng, IJ foot high, was found to have a root above 

 3 feet long. The stem and the root serve jointly as a 

 magazine for storing up the organisable matter to be 

 used next year in restoring all the external organs of 

 nutrition. When the stems of lime trees, alders, or 

 willows have been cut down, they will, if lying in shady 

 moist places, shoot out afresh, often after the lapse of 

 years, and produce numerous twigs a foot long or more, 

 covered with leaves. 



The pauses which occur in the seed-bearing of forest 

 trees are similar to those which are observed in most 

 perennial plants, which, when growing on a poor soil, will 

 also take several years to collect the conditions necessary 

 for the production of fruit (Sendtner, Eatzeburg). 



The loss of inorganic food-constituents, which the 

 fohaceous trees suffer by the fall of the leaves, is trifling. 

 When the leaves have attained their full formation, the 

 cells of the bark receive a copious supply of amylum, 

 which substance completely disappears from the cells in 

 the boss of the leaf-stalk (H. Molil). Even long before 

 the fall of the leaves, their sap is considerably diminished, 



