LETTER XIX. 



209 



naturally will, if allowed — taking due care where 

 necessary, in conducting the latter operation (while 

 not deferring it too long), not to withdraw, by over- 

 thinning, the support and shelter which the trees 

 give to one another. All this, indeed, the practical 

 forester knows very well, and habitually acts upon ; 

 but I think my theory explains the reason better 

 than the old. 



7. Secondly, The fact of the tree-plants of one year 

 being essentially independent of those of the past and 

 the next, and of each year's crop of timber essentially 

 standing by itself - — varying in quality, no doubt, as 

 in quantity, as is the case with the cereals and their 

 produce, — may perhaps furnish a good ground of 

 hope to the land-owner that a disease affecting his 

 plantations this year — and even for a series of succes- 

 sive years — may be purely temporary^ and not in the 

 end blight his prospects in respect of them. JiTo 

 doubt, even on the supposition that every tree is 



one integer," or an individual plant, that hope may 

 be entertained. Disease, as a general fact, is in its 

 own nature temporary, and on this ground alone a 

 diseased plantation might be expected in the course of 

 time — either spontaneously or by the aid of suitable 

 appliances (among which efficient drainage* seems to 



* " Since I came to Arniston as forester, I have recovered a 

 considerable extent of young larch plantations, which were fast 

 going back, and that simply by draining the soil, in order to draw 



O 



