12 NOTES ON POPES TR Y. 



to another hillside, only dotted with large trees, 

 and the interspaces at foot covered with a dense 

 undergrowth, or deprived of its rich carpet of 

 humus, and supporting only grass, we should not 

 infer, in the case of gregarious trees, that the 

 existing sprinkling came up under present condi- 

 tions, but that they are the survivors of a once 

 close forest, the mass of which went down under 

 conditions unfavourable to reproduction. Careful 

 research has established the view that perfect and 

 thorough reproduction is largely dependent upon 

 a gradual removal of the existing older stock. 

 In the rich forest soil of the Plains, if a forest 

 tract be cleared, there will ordinarily spring up 

 a mass of coarse herbage and undergrowth, through 

 which coppice shoots may readily find their way, 

 but through which young seedlings will rarely be 

 able to struggle ; and on steep hillsides the chances 

 of reproduction following a clean sweep are still 

 more precarious. Under the forest shade the soil 

 is in a state of perpetual increment from humus 

 afforded by decaying foliage and trunks ; the roots 

 hold it together ; the branches break the violence 

 of the rainfall ; the spongy absorbent nature of 

 the soil enables it to retain it ; and this, slowly 

 sinking into the underlying rock, preserves the 

 needful moisture in the soil, and becomes the 

 source of perennial springs. But if such a nioun- 



