COW TREE. In Caraccas, the palo de vaca, or cow tree, yields, from incisions made in its trunk, a vegetable milk of a nutricious quality, used plentifully by the negroes. This juicy matter is described as glutinous, tolerably thick, destitute of all acrimony, and of an agreeable and balmy smell. M. de Humboldt says that they drank considerable quantities of it in the evening, before they went to bed, and very early in the morning, without feeling the least injurious effect; the viscosity alone rendering it a little disagreeable. The tree, it seems, has not been described or classed by botanists, but it is supposed to belong to the sapota family, of which the butter tree of Mungo Park is another member. It is represented as a beautiful tree, rising like the broad-leaved star-apple (chrysophylum cainito). The milk exposed to the air produces a coagulum, which the people call cheese. The following reflections are in the best manner of M. de Humboldt:-- "Amid the great number of curious phenomena which have presented themselves to me in the course of my travels, I confess there are few that have so powerfully attracted my imagination as the aspect of the cow tree.-- Whatever relates to milk, whatever regards corn, inspires an interest, which is not merely that of the physical knowledge of things, but is connected with another order of ideas and sentiments. We can scarcely conceive how the human race could exist without farinaceous substances; and without that nourishing juice which the breast of the mother contains, and which is appropriated to the long feebleness of the infant. The amylaceous matter of corn, the object of religious veneration among so many nations, ancient and modern, is diffused in the seeds, and deposited in the roots of vegetables; milk, which serves as an aliment, appears to us exclusively the produce of animal organization. Such are the impressions we have received in our earliest infancy; such is also the source of that astonishment which seizes us at the aspect of the tree just described. It is not here the solemn shades of forests, the majestic course of rivers, the mountains wrapped in eternal frost, that excite our emotion. A few drops of vegetable juice recall to our minds all the powerfulness and fecundity of nature. On the barren flank of a rock grows a tree with coriaceous and dry leaves. Its large woody roots can scarcely penetrate into the stone. For several months in the year not a single shower moistens its foliage. Its branches appear dead and dried; but when the trunk is pierced, there flows from it a sweet and nourishing milk. It is at the rising of the sun that this vegetable fountain is most abundant. The blacks and natives are then seen hastening from all quarters, furnished with large bowls to receive the milk, which grows yellow, and thickens at its surface. Some empty their bowls under the tree itself; others carry the juice home to their children. We seem to see the family of a shepherd, who distributes the milk of his flock. "I have described the sensations which the cow tree awakens in the mind of the traveller at the first view.-- In examining the physical properties of animal and vegetable products, science displays them as closely linked together; but it strips them of what is marvellous, and perhaps also of a part of their charms, of what excited our astonishment. Nothing appears isolated; the chemical principles that were believed to be peculiar to animals, are found in plants; a common chain links together all organic nature."