18 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
1. PRESENCE OF SEED-BEARING TREES. 
In order to eliminate the chances of failure, and to benefit the 
production of seed, the crowns of the old trees ought to be well 
exposed to sunlight, so as to stimulate the production of flowers 
and fruit. When coniferous trees are crowded together, the 
cones are invariably small, and the germinative power of the 
seed is weak. Therefore a few of the most vigorous trees, or 
at least such a number as may be necessary, should be carefully 
isolated a few years before the main crop is cut. When thinning 
is required, the first aim is to remove all such trees as are not 
desired to reproduce themselves, such as birch, which springs 
up like a weed whenever an opening occurs, and which, if left 
alone, will overrun the ground and check other species. Partly 
suppressed trees are next removed, and those with wide-spreading 
crowns occupying an unduly large growing-space. ‘The extent 
to which a wood should be thinned when approaching maturity 
depends, of course, on the density of the crop, and while the 
thick parts may perhaps have to be thinned freely, the thin 
parts may sometimes remain almost untouched, or possibly the 
whole may be left until seed-production. 
2. SOIL SUITABLE FOR THE GERMINATION OF THE SEED 
AND THE GROWTH OF THE PLANT. 
The average Scottish woods, being usually rather thinly 
stocked, are often more or less over-grown with weeds, such as 
rough heather, bramble, bracken, bilberry, and thick masses of 
wire-grass and moss. The first three are not generally difficult 
to dispose of. Heather, when very dry, can be destroyed by 
burning against the wind, so as to keep the fire partly in check 
and to burn closely. After burning, however, the soil is seldom 
in a fit state to receive seed, and soil-preparation has to be 
resorted to, as will be dealt with later on. Brambles can be cut 
or grubbed up, the latter being by far the preferable method, as it 
also serves to loosen the soil and make it more suitable as a 
seed-bed. The heads of bracken are easily nipped off when they 
begin to form; and, generally, wherever bracken is growing, low 
weeds are kept so much in check that the mineral soil is usually 
to be seen, which forms a good seed-bed. The other weeds are 
not so easy to cope with. Where Jdz/berry exists in masses, 
natural regeneration is well-nigh impossible, as it forms such a 
