In these a hard, inflexible shell forms around the inner portions, the tree increases little in diameter, and no woody layers are found. To this class belong the Palms, of which Fig. 3 is an illustration. The age of this class of trees is estimated by comparing specimens with others whose age is known, or from an ascertained rate of growth. The oldest palms may not exceed five centuries, and their average period is probably less than 200 years. The height of the tallest of the species is said to be 192 feet. Trees growing in dense forests are comparatively short-lived, and attain less bulk than those in open places, where side-branches develop in the unobstructed rays of the sun. In similar conditions the age and dimensions attained by trees of each species are tolerably constant. Thus the average period of oaks and pines may be 300 or 400 years; but the exceptions are so numerous and wonderful, that we shall present in this paper a few of the most interesting and best-authenticated instances.
Of the white-pines, once the glory of the New England forests, we are not aware that any have been found more than 430 years old. Nor have we any oaks of extraordinary age. The Charter-oak at Hartford may have been a small tree at the first settlement of New England. The Wadsworth oak, at Geneseo, New York, is said to be five centuries old, and 27 feet in circumference at the base. The massive, slow-growing live-oaks, of Florida, are worthy of notice, on account of the enormous length of their branches. Bartram says: "I have stepped 50 paces in a straight line from the trunk of one of these trees to the extremity of the limbs."
The oaks of Europe are among the grandest of trees. The Cowthorpe oak is 78 feet in circuit at the ground, and is at least 1,800 years old. Another, in Dorsetshire, is of equal age. In Westphalia is a hollow oak, which was used as a place of refuge in the troubled times of mediæval history.
The great oak at Saintes, in Southern France, is 90 feet in girth, and has been ascertained to be 2,000 years old. This monument, still or recently flourishing, commemorates a period which antedates the first campaign of Julius Caesar!
The oriental plane-tree is noted in Eastern countries for its size and longevity. Fig. 4 represents one near Constantinople, which is 100 feet high, and 150 feet in circuit. It has been suggested that this is really a group of trees originally planted near together for their shade. The figure, however, hardly confirms that opinion, and many trees of this species are mentioned by travellers not greatly inferior to this one in dimensions.
Most of the old plane-trees are hollow, their tops being sustained by wood of recent growth. In this respect an exogenous tree resembles a coral-reef, where the vitality and growth are at the surface only.
Of chestnuts, we have the famous one at Tort worth, in Glou-
