Every one is acquainted with certain plants that secrete a milky fluid in peculiar ducts known as "milk ducts." The lettuce, silk-weed and sumach may be mentioned as well-known illustrations. In tropical countries there are numerous trees that secrete a milky substance, which, however, differs very widely in its properties in the different species of trees that produce it. From some kinds the milky juice is bitter, nauseous and poisonous; but in others it is very pleasant and agreeable to the taste, and very nutritious as an article of diet. Among this class is found the Cow Tree. This tree flourishes in Central and South America. It is known by the name, Palo de Vaca, to the inhabitants, but to botanists it is Brosimum galactodendron, and is a member of the fig family. This tree is said to grow on the surface of the rocks, sending its roots downwards with great difficulty. Its leaves are rather thick and fibrous, having a dry bark-like appearance. For many months of the year no showers fall upon it and its branches look dead and withered. But when the bark is pierced there is a copious flow of sweet, nourishing milk. This is used extensively by the natives as a drink diet, and it is said they become visibly fatter during the season of its most copious flow.

The flow of the liquid is most abundant at sunrise, at which time the natives flock to the forests of cow trees, carrying their pitchers to receive the supply of milk. Some drink it on the spot, while others carry it away to their homes.

When left standing in the open air, a thin, tough skin is formed on the surface, and as this is taken off it continues to form for a considerable time. This may be kept and used as a cheese, for a week or more. When placed over a fire a scum of cream forms on the surface, which if removed and the heat is kept up steadily, the milk gradually thickens to a paste; then oily rings form on the surface, similar to those that are seen on cream that has been for some time over the fire. Finally this fat portion envelops the whole mass, which then exhales an odor precisely similar to that from roast beef. Boussingault visited the region where this tree is found and gives the following account of the results of a careful examination of the milk. In order that its resemblance to cow's milk may be the more readily understood, he gives a comparison of the milk of the cow tree with the cow's cream. He finds the vegetable milk to contain : "1st, a fatty substance resembling wax, fusible at 500 C, which represents the butter of natural milk. 2d, a nitrogenized substance very much analogous to cheese. 3d, saccharine substances. 4th, salts of potassium, sodium and magnesium, together with phosphates." The following gives his comparison of the animal and vegetable products :

When the milk of the cow tree is kept in a closed vessel for two months it separates into two parts; one, a light yellow liquid with a slightly sour odor; the other, a solid, white and insipid, and that is insoluble in either water or alcohol. This is the fat or wax found so abundantly in the milk. This substance burns with a brilliant green flame. This tree is found in Brazil, where it is sometimes called Galactodendron dulce, under the mistaken idea that it is a different tree from the one described above. Another, G. clusia, found in that country, furnishes a milk quite agreeable to the taste, but it is quite inferior to that already named, as it is difficult to purify it, and instead of wax it contains an unpleasant resinous substance. Other trees furnish milk that is poisonous; but of these I do not propose to speak at present.

Canon City, Col.