There is a juice in the bark of trees, which must be looked upon as their blood, though it is not of a similar nature in all. In the fig it is of a milky consistency, and has the peculiar property of curdling milk, and so forming cheese.[1] In the cherry-tree this juice is gummy, in the elm clammy, in the apple viscous and fatty, while in the vine and the pear it is watery. The more viscous this humour is, the more long-lived the tree. In a word, we find in the bodies of trees-as with all other beings that are animated-skin, blood, flesh, sinews, veins, bones, and marrow; the bark serving them in place of skin. It is a singular fact connected with the mulberry-tree, that when the medical men wish to extract its juice, if the incision is lightly made, by a blow with a stone, and at the second hour of the day in spring, the juice will flow: but if, on the other hand, a wound is inflicted to any depth, it has all the, appearance of being dried up.

Immediately beneath the bark in most trees there is a fatty substance, which, from its colour, has obtained the name of alburnum:[2] it is soft, and is the very worst part of the wood, and in the robur even will very easily rot, being particularly liable to wood-worm, for which reason it is invariably removed. Beneath this fat lies the flesh[3] of the tree, and then under that, its bones, or, in other words, the choicest part of the wood. Those trees which have a dry wood, the olive, for instance, bear fruit every other year only: this is more the case with them than with those the wood of which is of a fleshy nature, such as the cherry, for instance. It is not all trees, too, that have this fat and flesh in any abundance, the same as we find to be the case among the more active animals. The box, the cornel, and the olive have none at all, nor yet any marrow, and a very small proportion, too, of blood. In the same way, too, the service-tree has no bones, and the elder no flesh, while both of them have marrow in the greatest abundance. Reeds, too, have hardly any flesh.