93 



the dust blown from the street into the depressions of the wounded surface, 

 in which seeds of all kinds of weeds find instant lodgment. Now if a wil- 

 low-seed falls into one of these accumulations of soil, the young seedling 

 finds space for development and its roots finally reach the soil through the 

 rotted wood of the old trunk. When an adventitious root of especial length 

 grows downward from the pollarded surface at the crown of the tree, with- 

 in the hollow trunk, it has the appearance of a young trunk. 



Fig-. 4. Stilted spruce near Schc^iiinzach in Stiibewasen. (After L. Klein.) 

 A case, due probably to the same conditions, which cause the stilt-like 

 growth of spruces, was shown as recently as the 8o's of the last century in 

 Kohlhasenbriick near Neubabelsberg (District of Potsdam). The stump 

 of an old oak, about 75 cm. high on the village street, had formed a broad 

 hollow cylinder by the rotting of all of the heart wood. This was half filled 

 with rotten wood and earth and a healthy oak, possibly thirty years old, 

 stood in this as in a sheath. 



In spruce plantations one finds at times the so-called "Harp-trees" in 

 which a number of side branches have become elevated at right angles to the 



