352 



by draining wet soils; (3) by loosening and mixing heavy soils with earths 

 rich in humus, so that the warmth of the air can penetrate more easily. 



B. Lessening of sharp contrasts by shading: (i) by brushing the seed 

 beds with evergreen boughs, w^hich should not be removed on warm days ; 

 (2) by making the seed beds in places which are protected on the south by 

 tracts of trees, 



"In the restoration of pine woods, on the wliole, the most radical means 

 consists in a return from the extensive clearing system to a plan of seeding, 

 such that the young plants have tlie necessary protection from the direct 

 sunlight in the overhead wood protection, but can still obtain as much light 

 as is necessary for their vigorous development. The same end is attained 

 by a slender fringe of trees running from N. E. to S. W., which are much 

 used at present in the restoration of the pine tracts. In the cultivation of 

 extensive clearings the shading can be obtained by a shelter growth of such 

 plants as are favored by the habitat, — for example, by birches, etc., or by 

 previous spruce plantations." 



"In cases, where no shelter growth can be arranged because of 

 local conditions, the planting of seedlings is preferable (yearling plants with 

 a good root system seem best suited for this), yet the first two cultural 

 methods will much more surely attain the desired goal." 



Finally it is well to emphasize that every attention should be given to 

 obtaining a good root system; — accordingly, too thick seeding, heavy, un- 

 broken soil, considerable injury in transplanting and the like are to be 

 avoided. 



A leaf casting occurs also in older trees. The older needle bunches of 

 plants standing on moor-soils in misty depressions, or found in localities 

 subject to extreme frost, fall prematurely. But, in the autumn, these hang 

 to the trees, turning yellow or drying up, and are thus distinguished from 

 the seedlings specifically diseased with leaf casting. On heavy soils the 

 pine always dies easily^. 



Leaf-Fall in House Plants. 



Among the most delicate of the house plants belong the azaleas, be- 

 cause, as a rule, they suddenly drop their leaves in summer or in the 

 autumn; the broom-like little tree then at best develops only a few pitiful 

 flowers. Here too are concerned sharp contrasts occurring suddenly. Either 

 the plants (usually set in moor soil) in summer are left too dry, and later 

 watered very abundantly, or they are brought too suddenly into the warm 

 house in the autumn. In both cases, the leaves are weak functionally and 

 then their functioning is increasingly stimulated by the increased upward 

 pressure of the water. If the transition is brought about gradually, the inac- 

 tive leaf surfaces would have time to resume their normal action by a general 

 slow increase in their turgidity and there would be no resultant injury. 



1 Runnebaum, A.. Das Absterlien iind die Bewirtschaftuner drr Kiefer im S^an- 

 genholzalter usw. Zeitschr. f. Forst- u. Jagdwesen, 1892, p. 43. 



