1726 ARBORETUM AND FRUTICETUM. PART III. 
The bark of Q. Siber furnishes suberine, the: suberic acid, and a product 
by far more important than that of any species of the genus, cork ; a substance 
which is not produced by any other tree whatever, in sufficient quantities to 
be applied to any useful purpose. 
The leaves, the flowers, and the fruit, according to Bosc, afford nourish- 
ment to more than 200 species of insects, even in the neighbourhood of Paris ; 
and some of these insects are either valuable themselves in the arts, or they 
are the cause of excrescences, such as oak galls, which are valuable. The 
leaves of Q. coccifera afford nourishment to the Céccus {licis, a hemipterous 
insect, which is used in medicine under the name of kermes, and has been 
employed in dyeing scarlet, from the remotest antiquity, under the name of 
scarlet grain. This insect is produced, and cultivated for commerce, in the 
south of France, and in various parts of the south of Europe, and of the East. 
Oak galls, which are much in demand for the manufacture of ink and for dyeing 
black, are produced on most of the deciduous European species, and are very 
abundant on the section Robur; but the galls of commerce are chiefly pro- 
duced by the Q. infectoria, a native of Asia Minor and the adjoining countries. 
All the smaller parts of oaks, such as the spray, buds, leaves, flowers, and 
- fruit, may be employed in tanning; and, accordingly, the cups, or calyxes, of 
some species are in use for this purpose, more particularly those of the valonia 
oak (Q. Ai’gilops), a native of the Archipelago. The leaves of the section 
Robur are used as a substitute for spent tanner’s bark in hot-houses; and 
being slow in decomposition, are found to retain the heat for a longer period 
than those of any other European trees. 
The acorns of all the species are edible ; and, in every country where the 
oak abounds, they form the most important part of the food of wild quadru- 
peds of the fructivorous or omnivorous kinds, and of some birds. The wild 
animals most useful to man, which are nourished by them, both in Europe 
and America, are the wild boar, the stag, and the goat. In Asia, pheasants 
and pigeons, with other birds in a wild state, eat acorns, no less than wild qua- 
drupeds. In North America, cows, horses, swine, bears, squirrels, pigeons, 
and wild turkeys devour them. Among the domestic animals which eat and 
thrive on acorns, the principal is the swine; but there are few animals and 
birds, in a state of domestication, Bose observes, that may not be made to 
live and thrive on them, however unwilling they may be to touch them at 
first. In the earlier ages, there can be no doubt that acorns, in the countries 
where they were produced, were the food of man; and they are still, as we 
have seen, eaten in some parts of the south of Europe, the north of Africa, 
and the west of Asia. The kinds which produce the acorns most valued 
for eating are, Q. Ilex, Q. Ballota, Q. gramuntia, and Q. E’sculus. The degree 
of bitterness in acorns, produced by the same species, varies exceedingly on 
different trees ; and were any kind of oak to be introduced into orchards as a 
fruit tree, it would be advisable to select only the best varieties of particular 
species, and propagate these by grafting. There are even varieties of Q. 
Robur which produce acorns much less bitter than others; and we have 
received some from a tree of this species, in the south of France, which ac- 
cording to Dralet, are so sweet as to be eaten by the inhabitants. (See Re- 
cherches sur les Chénes a Glands doux, p. 178.) 
The entire tree or shrub, in the case of every species of oak, may be con- 
sidered as highly ornamental: the least so are the willow-leaved oaks, and 
the most so the lobed and deeply sinuated leaved kinds. The foliage, even, 
of the ‘same species, and more especially of the deciduous kinds, varies ex- 
ceedingly ; not only on different individuals, but on the same individual at 
different seasons of the year. In spring, the leaves of many of the decidu- 
ous kinds are small, delicate, and beautifully tinged with yellow and red; in 
summer, they are broad and green; and in autumn, coriaceous, and of a 
russet brown, scarlet, or blood-red colour. Nothing can be more remarkable 
than the variation in the forms of the leaves, in the same individual, in some 
of the American species; those of the tree, when young, being sometimes 
