198 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
tree. These 42 reduced by 20 per cent. are brought down to 34 
cubic feet, so that the average size is rather greater than that 
assumed for Scottish timber of the same age, although the latter 
may be too lowly estimated. The fact must also be taken into 
account that the greater part of the earlier thinnings from the 
German woods are little but firewood, although the accumulating 
interest on the sums realised for the latter gives them considerable 
importance by the end of the rotation. Taking everything into 
consideration, it is probable that, after all, there is not so much 
difference between the total yields in both cases; but when quality 
is considered, the German timber would probably have the prefer- 
ence. The constant struggle which goes on during almost the whole 
period of growth causes a natural pruning of side branches to go 
on continually, so that it is rare to find a branch or large knot on 
the stems of the larger trees at a less height than 60 or 70 feet 
from the ground. The growth of the wood, too, is remarkably 
uniform, and eccentric wood-rings are rarely seen, even in the centre 
of the butt end. These two conditions are about all that are 
necessary for producing the best class of fir timber, and were the 
timber grown under the two methods in the same market, the 
German growth would undoubtedly fetch a higher price, as a rule, 
where quality and size were most in demand. 
I have compared soils ranked as belonging to the first class, or 
best quality, in Germany with average plantation soils in Scotland, 
because I consider the latter to be superior to the former as a rule. 
In Germany only the worst description of soil is devoted to forestry, 
while in the lowlands of Scotland many plantations exist on soil 
that might be, and in many cases has been, devoted to agriculture, 
so that an average would probably be struck at about the same 
quality of soil in both cases. In regard to climate and elevation, 
the German woods probably have the best of it, in so far as their 
ultimate height growth is affected, but the difference is too slight 
to justify a proper comparison being made, as the length of the 
growing season makes less difference to the Scots fir than is the 
case with many trees. 
Although this system of natural selection appears to give the 
best results on good soils, and where the trees are sufficiently 
vigorous to carry on a lengthened struggle, it is questionable if 
it is the best method of treatment on the inferior soils, where 
the trees can derive little nourishment from the ground. In such 
cases the retention of a certain proportion of branches is of much 
