—M. Humboldt and his com-panions, in the course of their travels, heardan account of a tree which grows in thevalleys of Aragua, the juice of which is anourishing milk, and which, from that cir-cumstance, has received the name of thecow-tree. The tree in its general aspect re-sembles the chrysophyllum cainito; its leavesare oblong, pointed, leathery, and alternate,marked with lateral veins, projecting down-wards; they are parallel, and are ten incheslong. When incisions are made into thetrunk, it discharges abundantly a gluti-nous milk, moderately thick, without anyacridness, and exhaling an agreeable balsa-mic odour. The travellers drank consider-able quantities of it without experiencingany injurious effects; its viscidity only ren-dering it rather unpleasant. The superin-tendent of the plantation assured them thatthe negroes acquire flesh during the season in which the cow-tree yields the greatestquantity of milk. When this fluid is ex-posed to the air, perhaps, in consequence ofthe absorption of the oxygen of the atmos-phere, its surface becomes covered withmembranes of a substance that appears tobe of a decided animal nature, yellowish,thready, and of a cheesy consistence. Thesemembranes, when separated from the moreaqueous part of the fluid, are almost aselastic as caoutchouc; but at the same timethey are as much disposed to become putridas gelatine. The natives give the name ofcheese to the coagulum, which is separatedby the contact of the air; in the course offive or six days it becomes sour. The milk,kept for some time in a corked phial, haddeposited a little coagulum, and still exhal-ed its balsamic odour. If the recent juicebe mixed with cold water, the coagulum isformed in small quantity only; but the se-paration of the viscid membranes occurswhen it is placed in contact with nitric acid.This remarkable tree seems to be peculiarto the Cordilliere du Littoral, especiallyfrom Barbula to the lake of Maracaybo.There are likewise some traces of it near thevillage of San Mateo; and, according tothe account of M. Bredmeyer, in the valleyof Caucagua, three days journey to the eastof the Caraccas. This naturalist has like-wise described the vegetable milk of the cow-tree as possessing an agreeable flavour andan aromatic odour; the natives of Caucaguacall it the milk-tree.