142 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
grown and suppressed. The latter will from time to time be 
removed in the thinnings, and although these will be valuable in 
proportion to the size of the stems that furnish them, the effect 
upon the financial returns as a whole will be less than if the 
volume of the final felling were also seriously reduced. Of course, 
if the whole of the seed used to furnish the plants for a pure 
wood is of small size, the loss will be quite as great as, in fact 
rather greater than in the case of the mixed wood; but if the 
seed is a mixture of small and large individuals, natural differ- 
entiation, aided by artificial thinning, will secure the largest 
stems—that is, the produce of the largest seed—for the final 
crop. 
In a year when nearly every oak is bearing a crop of acorns, 
one finds that the size of the fruit varies much on different trees. 
If the tendency to bear large fruit is in any sense hereditary, and 
if small fruit means slow-growing trees, it follows that in a 
natural forest the trees that reach maturity and bear seed— 
that is, that propagate the species—must chiefly belong to the 
large-fruited varieties. In the course of time one may therefore 
expect to find an increase in the average size of the fruit or seed 
of any species of tree, but where the duration of the generation 
is to be reckoned in hundreds of years—as, for instance, in the 
case of the oak grown in natural forests—the inquiry becomes 
one that is almost paleeo-botanical in its character, and possibly 
may never have been undertaken. , 
When young trees are being sent out from the nursery, it is a 
common practice to retain those that are of small size, so that the 
further growth of two or three years may make them of a more 
attractive size. Suppose, for instance, that 70 per cent. of all 
the plants in a bed of five-year-old oaks are 3 feet high, and are 
sent out, while the 30 per cent. which are less than 3 feet in 
height are transplanted into a fresh plant-bed and retained. 
Let it be further supposed that it is not till they are seven years. 
old that the plants originally rejected reach an average height of 
3 feet. The question then comes to be—Are young trees of 
varying age, but of the same size, all alike suitable for planting, or, 
in other words, are one thousand of the above-indicated seven- 
year-old oaks as valuable as the same number of the younger age? 
For my own part I doubt if they are, and, further, I think it is 
probable that if such slow-developing individuals are alone 
depended on to represent any particular species in a wood, 
