198 CAUSE OF DISEASE AMONG 



every tree sound, and of excellent quality of timber ; 

 while at the same time, every tree in this position 

 was at least three times as large as those planted in 

 the interior level parts of the plantation, although 

 all were of the same age. Now, the cause of this 

 superiority of the trees which grew upon the sloping- 

 bank may at once be seen, from what I have already 

 said upon the point. Again, another side of this 

 plantation was bounded by a deep ditch, forming a 

 fence upon the edge of a field ; and all along this 

 ditch upon the side of the wood, larch trees of ex- 

 cellent size and quality were growing. Nothing can 

 be more convincino- than this, that in order to grow 

 larch timber of sound and good quality upon land 

 which formerly grew diseased trees, all that is re- 

 quired is to drain it, when success will be the result. 

 I have always found larch trees succeed better 

 when growing among hard-wood trees, than when 

 growing by themselves, or among other firs, even 

 although planted upon soil in the same state in both 

 cases ; and the cause of this, I conceive, to be that the 

 roots of the hard-wood, from their penetrating deeper 

 into the earth than those of the fir, have a tendency 

 to divide the soil, and open it up for the more ready 

 circulation of the water through it. It is, indeed, 

 well known to almost every forester, that the roots 

 of the hard-wood trees will penetrate through the 

 stiffest soil, and considerably break up and improve 

 it, to the depth of about two feet ; and when the 



