92 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
The explanation of these facts must be obvious to all, when we 
consider that a healthy plantation simply means a mass of healthy 
trees. A man needs little or no knowledge of forestry to enable 
him to discriminate between a thriving and healthy tree and a 
diseased and stunted one; and every true artist will admire the 
former before the latter, because the healthy tree is the typical 
production of the great artist herself—Nature, the source of all 
art. Now every practical forester knows that a healthy and 
vigorous growth can only be insured by the careful selection of 
those plants which are thoroughly well adapted to soil, climate, 
and situation. Although it would perhaps be going too far to 
say that indigenous plants can alone supply what is required in 
this respect, yet when we consider the various diseases and 
climatic affections to which introduced trees are subject in this 
country, coupled with the fact that they rarely retain their timber 
qualities when removed from their native habitat, we may safely 
infer that if we want to see a healthy and vigorous growth main- 
tained throughout the lifetime of our plantations, we must content 
ourselves with those species which nature has provided with a 
constitution strong enough to withstand our changeable tempera- 
ture and uncertain climate, and leave recent introductions outside 
the bulk of our woods until careful experiments in various soils 
and situations have determined their particular requirements in 
these respects. 
And with regard to the third point, viz., their relation to local 
industries, the importance of healthy woods is made still clearer, 
We usually find that any industry which owes its existence to the 
manufacture of articles of commerce from or out of the raw 
material, is located in the neighbourhood from which the raw 
material is obtained. The reason for this is obvious, and needs 
no explanation, Now, although the industries connected with 
woods in this country are comparatively unimportant when 
considered individually, yet when taken collectively we find that 
they occupy a more important place in regard to the prosperity of 
the country than would at first sight appear. It is true that 
woods neither bring in money nor employ much labour for the 
greater part of their growth, but this is exactly the period in 
which they exercise the most beneficial effects on the adjoining 
agricultural lands. Their relation to climate, rain-fall, water- 
supply, ete., is also considerable, but which can only be merely 
referred to here. But during their formation and earlier stages, 
