Some specimens of supposed hybrids between the peach and the plum were sent to the Academy for examination. The chief reasons for the belief that they were hybrids were that they were sterile, and seemed in leaf and branches intermediate between the two species. Mr. Meehan observed that in hybrids between acknowledged species, it did not follow that the characters should be intermediate. Often there would be scarcely any trace of the action of the male parent, while at other times the male would seem to have had a leading influence. But these plum branches showed no trace of any intermediate characters, but were purely plum branches, with no trace of the peach character about them.

He said he had called the attention of the Academy on several occasions in the past to the fact that the bark of trees did not crack from the mechanical pressure of wood-growth, as so often taught in botanical text books; but the rifts arose from the peculiar growth of cork cells, and it was the character and general direction of these growths, apparently different in species, that gave the varied characters to tree bark - characters that were more or less constant in each species of tree. A tree could in fact be nearly as well known by its bark as by its fruit. The development of the cork cells destroyed the cuticle In the cherry and birch the chief development was in a lateral direction, and hence we could easily strip sections from around branches. In the Abele poplar the development destroyed the bark to a considerable depth, and in a quadrangular form. These gradually met at the points and at once formed deep furrows up and down the stem. In the plane and some other trees, the cork cells worked up and down under thick layers of bark which it threw off in flakes. But the chief distinction was in the the period of life when they assumed activity.

In the chestnut (Castanea) it was nearly twenty-five years before they grew into destructive agencies, and hence there was smooth bark to the chestnut for nearly a quarter of a century. In the oak rough bark from the development of the cork cells, began at about ten years; in the sassafras at five years; in some they started at one, and ac-casionally the same season. In the beech they grew the first season, and only worked under the outer cuticle, which they threw off as fine film annually. Handling a branch of beech at some seasons, a filmy deposit would be left in the hands, which was the fine silky bark of the beech. Hence the beech had never rough bark. This fact should show mechanical action has no part in rifting the bark. Mechanical action should split a beech as well as any other tree.

Returning to the plum, he remarked that the development of the cork-cells were in many respects the same as in the beech. They started on their destructive errand before the annual growth was fairly over, destroying the thin outer cuticle as it progressed. It was this that gave the silvery tint to plum-wood, with which all must be familiar. This was never seen on peach-wood. This character was exhibited on all the samples of supposed hybrids sent. There was nothing whatever to distinguish them from pure plums so far as this character was concerned.

As for the flowers, the plants were sterile because of peculiar abortion in the reproductive organs. The carpels instead of being consolidated, ending in a single style as in the ordinary plum, had become distinct, and there were ten processes difficult to say whether they resembled stamens or pistils most. There were no attempts to form perfect stamens or petals, but the bud scales had a faint rosy margin as if there existed a slight disposition to make petals out of them. They were remarkable examples of monstrosity in plum flowers, but nothing to indicate any action of the peach therein. They were evidently sterile because they were monstrous, and not that they were hybrids. The foliage had a more peachy look than customary with plums, so far as mere outline was concerned, but it is well known that when there was a disturbance of sexual characters, the whole system of growth was apt to be disturbed. It was possible the plum and the peach would hybridize. It would be of much interest to science could the possibility be proved a fact. It was due to science to say these specimens did not prove it.

The chief interest in the specimens, he thought, dwelt in the fact that amidst all the changes in characters brought about by some abnormal agency, the cortical peculiarities, as influenced by the cork-cells, remained the same. - Proceedings of Academy of Natural Sciences of Phila.