NATURAL SCIENCES OF PHILADELPHIA. 239 



The corundum is the pure material, and is not emery. The 

 masses are made up of a close aggregation of crystals with the 

 intervals occupied with margarite. Some of the fissures and sur- 

 faces of the masses display large and beautiful crystalline plates 

 of margarite, and occasionally unusally fine crystals of diaspore. 

 Some of the crystals of corundum appear to have undergone par- 

 tial metamorphosis into margarite. The corundum is bluish-gray, 

 of very compact texture, aud does not cleave so readily as the 

 North Carolina mineral. 



The various specimens of corundum and other minerals found 

 iri association with it, presented to the Academy this evening by 

 Mr. Ball, were obtained at the locality described. 



October 8. 



The President, Dr. Ruschenberger, in the chair. 



Seventeen members present. 



Mr. Thomas Meehan remarked, that as botanists well knew, 

 Quercus prinoides seldom grew more than two feet in height. It 

 was one of the smallest of shrubs. In his collections in Kansas, 

 he found oaks in the vicinity of Leavenworth, which made small 

 trees from ten to fifteen feet high, and with stems from one to two 

 feet in circumference. He was entirely satisfied that it is identical 

 in every respect but size with the Q. prinoides of the eastern 



States. 



Among trees there are few which produce forms as low shrubs ; 

 but the Pinus Banksiana, in the East but a bush of five or ten feet, 

 grew often forty feet along the shores of Lake Superior ; the Gas- 

 tanea pumila, Chinquapin chestnut, when it gets out of the sands of 

 New Jersey into the clayey soils west of the Delaware, often grew 

 as large as many full grown apple trees; while the Geltis occiden- 

 talism which in the East is generally but a straggling bush along 

 fence corners, is in Ohio a large spreading tree with enormous 

 trunk, and in Indiana is as lofty and as graceful as an elm. 



He also exhibited a section of a stem of Wistaria sinensis, and 

 called the attention of members to a curious arrangement of the 

 wood and bark. The vertical section showed by the annual rings 

 of wood that it was about twelve years old. After the eighth 

 year's circle there was a layer of bark, and over this layer two 

 more circles of wood. On a portion of the section another layer 

 of bark had formed between the tenth and eleventh years' circles 

 of wood. The bark seemed to be wholly of liber, the cellular 

 matter and external cortical-layer of the regular bark appeared to 

 be wanting. A longitudinal section showed where these internal 

 layers of bark extended no further upwards, and at this point there 



