One of the strongest arguments in favor of the theory of the recent deposition of the gem is connected with its discovery in the gold mines of the Adolfskoi in Siberia. Here they were found in alluvial strata twenty feet above those deposits which contained the bones of the mammoth and the rhinoceros. Hence Humboldt, Murchison, and Verneuil were led to the conclusion that they had been deposited there since the introduction of animal life. There are also some remarkable evidences to sustain the view that these gems were formed in the conglomerate and earth where they are now found. In some of the mines of India they have been taken out of red earth with the earth clinging to their sides as if it had become attached to them, while the crystals were of a soft, glutinous substance. In the Museum of Rio Janeiro there is a large rounded diamond which has very distinct impressions of grains of sand upon its sides. The British Museum contains an octahedral crystal attached to alluvial gold, and Dr. Nello Franka mentions another which enclosed a leaf of gold. A number of specimens have been observed containing splinters of ferruginous quartz and crystals of other substances. The microscope often reveals in the interior of these stones germs of fungi and even vegetable fibres of higher organization, some of which resemble the moss-like appearance seen in the moss agates. It was from the study of these conditions, connected with the fact that the stone becomes black when strongly heated, that Goppert was led to assert that it could not be of igneous origin. It was also from investigation of the refractive powers of the gem that Sir David Brewster was induced to assume the hypothesis that it was, or that it might be, a congealed secretion of a vegetable production. This distinguished philosopher was seeking a perfect lens for microscopic use; and discovered that the diamond, notwithstanding its immense refractive power, was of very doubtful character in its adaptation to this purpose, and that its laminæ were sometimes of different shades and even arranged in a series of stratification. They not only differed from each other in color and purity, but did not exhibit a common focus. Therefore, Brewster was led to infer from these and other phenomena that the mineral was of vegetable origin, and that its parts must have been held in solution before crystallization took place. There is nothing very startling in this hypothesis, no more so than in the case of the amber, which is now admitted to be a fossil resin, and which is, in its refractive powers, second only to the diamond. Therefore we cannot object to the theory of vegetable origin on account of the property of brilliancy.