[858] “Fuit.” From the use of this word he seems uncertain as to its existence in his time; the account is copied from Theophrastus, Hist. Plant. B. iv. c. 3. Fée suggests that he may here allude to the Baobab, the Adansonia digitata, which grows in Senegal and Sennaar to an enormous size. Prosper Alpinus speaks of it as existing in Egypt. The Arabs call it El-omarah, and the fruit El-kongles.
[859] The Mimosa polyacanthe, probably. Fée says that the mimosæ, respectively known as casta, pudibunda, viva, and sensitiva, with many of the inga, and other leguminous trees, are irritable in the highest degree. The tree here spoken of he considers to be one of the acacias. The passage in Theophrastus speaks of the leaf as shrinking, and not falling, and then as simply reviving.
[860] The Acacia Nilotica of Linnæus, from which we derive the gum Arabic of commerce; and of which a considerable portion is still derived from Egypt.
[861] These gums are chemically different from gum Arabic, and they are used for different purposes in the arts.
[862] The vine does not produce a gum; but when the sap ascends, a juice is secreted, which sometimes becomes solid on the evaporation of the aqueous particles. This substance contains acetate of potassa, which, by the decomposition of that salt, becomes a carbonate of the same base.
[863] This is not a gum, but a resinous product of a peculiar nature. It is known to the moderns by the name of “olivine.”
[864] The sap of the elm leaves a saline deposit on the bark, principally formed of carbonate of potassa. Fée is at a loss to know whether Pliny here alludes to this or to the manna which is incidentally formed by certain insects on some trees and reeds. But, as he justly says, would Pliny say of the latter that it is “ad nihil utile”—“good for nothing”?
[865] A resinous product, no doubt. The frankincense of Africa has been attributed by some to the Juniperus Lycia and Phœnicia.
[866] The Penæa Sarcocolla of Linnæus. The gum resin of this tree is still brought from Abyssinia, but it is not used in medicine. This account is from Dioscorides, B. iii. c. 99. The name is from the Greek σὰρξ, “flesh,” and κόλλα, “glue.”
[867] See B. xxiv. c. 78.