Page:Popular Science Monthly Volume 2.djvu/656

636 process invented by Jordery and Paschkoff for the solidification of petroleum, thus making it more easily and more safely transportable: "First make a decoction of the root or leaves of the Saponaria officinaria, quillay, or any other substance possessed of saponific properties. Then an amount of this decoction or extract, equal to one-twentieth of the petroleum to be solidified, is placed in a vat, and the petroleum suffered to flow in upon it slowly, the whole being constantly stirred in the mean time. This process may be followed with oils in general, and with volatile oils it will prevent loss from leakage and obviate many of the dangers now attending their transportation."

Curious Phenomenon in Vegetable Physiology.—It has long been known to botanists that, occasionally, after the felling of pine and fir trees, their stumps would continue to increase in diameter, i. e., form new woody layers for several years. Dutrochet mentions some cases of extraordinary longevity in the stock of Pinus picea after the trunk had been felled. He says that, in the year 1836, a stock of Pinus picea, felled in 1821, was still alive, and had formed 14 thin new layers of wood—that is, one each year; and another, felled in 1743, was still in full vegetation, having formed 92 thin layers of wood, or one each year. This singular phenomenon was long a puzzle to botanists and vegetable physiologists. Over thirty years ago Goeppert, an accomplished botanist of Breslau, undertook an investigation of the subject. The result is published at large in the "Annales des Sciences Naturelles" for 1843. It appears that in all the cases examined by Goeppert there was a union of the roots of the fallen trees with the roots of living trees growing in the immediate vicinity, and his explanation of the phenomenon was that the stumps maintained their growth by drawing their supplies of sap from the trees with which they were thus connected. The union of roots in these cases was sometimes woody, and sometimes only by the bark of the roots. So far as observed, this anastomosis, or natural grafting, is confined to coniferous trees, and to only a few species of them, chiefly the silver-fir, the spruce, and occasionally the Scotch fir. In the London Gardeners' Chronicle of August 31st is an account of an instance of this kind of anastomosis of the roots of a larch, and a figure is given of the specimen, in which the stump and its root-connections are exhibited. The cut stump shows rotten wood in the centre, with the new wood at the circumference surging over the edges of the wound.

Although the discovery of this root-union explains some of the questions involved in this curious phenomenon, it does not explain them all; for instance, why does not the sap, which is thus robbed from the roots of the nurse-tree, pass up in the usual channels and overflow at the top of the stump, as is the case when a grape-vine or deciduous tree is cut during the active ascent of the sap? As the growth of new wood in exogenous trees takes place from the cambium, and the cambium is supposed to be the sap which has been elaborated in the leaves, what is the source of the cambium in these stumps?

It would seem as if there was here a complete contradiction of the ingenious theory of some of the French botanists that wood growth begins in the leaves or leaf-buds, and descends continuously thence to the roots, so that, in fact, wood may be considered the united mass of roots which emanate from the leaves of the plant.

The theory of De Candolle is, that the woody and cortical layers originate laterally in the cambium furnished by preëxisting layers, and nourished by the descending sap. To use the words of De Candolle, "The whole question may be reduced to this: either there descend from the top of a tree the rudiments of fibres which are nourished and developed by the juices springing laterally from the body of the wood and bark, or new layers are developed by preëxisting layers which are nourished by the descending juices formed in the leaves." The latter part of this statement, though somewhat vague and unsatisfactory, probably involves the true theory of the formation of wood. The preëxisting layers mentioned in De Candolle's statement include the medullary rays which reach the circumference. These medullary rays are composed of cellular tissue derived from the pith, and, like it, are capable of indefinite extension by cell-multiplication.