Page:Hardwicke's Science-Gossip - Volume 1.pdf/188

There appears to be also a milk-tree common in the forests of Para which the natives call "Massenodendron," but of which we have no definite knowledge, except that it was for a considerable time used on board H.M.S. Chanticleer as a substitute for cow's milk. It was said to suffer no chemical change by keeping, neither did it show any tendency to become sour.

The most celebrated of all the cow-trees was that discovered and made known by Humboldt as the "Palo de Vaca," or "cow-tree." Singularly enough it belongs to a different natural order from those already mentioned (Artocarpaceæ), and to one which includes also the poisonous Upas-tree of Java. The botanical name of this cow-tree is Galactodendron utile, the "useful milk-tree," or, as more recently called, Brosimum utile. Its discoverer states that while staying at the farm of Barbula in the valleys of Aragua, "we were assured that the negroes of the farm, who drink plentifully of this vegetable milk, consider it a wholesome aliment, and we found by experience during our stay that the virtues of this tree had not been exaggerated. When incision are made in the trunk, it yields abundance of a glutinous milk, tolerably thick, devoid of all acridity, and of an agreeable and balmy smell. It was offered to us in the shell of a calabash. We drank considerable quantities of it in the evening before we went to bed, and very early in morning, without feeling the least injurious effect. The viscosity of this milk alone renders it a little disagreeable. The negroes and the free people who work in the plantations drink it, dipping into it their bread of maize or cassava. The overseer of the farm told us that the negroes grow sensibly fatter during the season when the Palo de Vaca furnishes them with most milk. This juice, exposed to the air, presents on its surface membranes of a strongly animalized substance, yellowish, stringy, and resembling cheese. The people call it cheese. This coagulum becomes sour in the space of four or five days.

"The extraordinary tree of which we have been speaking appears to be peculiar to the Cordillera of the coast, particularly from Barbula to the Lake of Maracaybo. At Caucagua the natives call the tree that furnishes this nourishing juice the "milk-tree" (arbol del leche). They profess to recognize, from the thickness and colour of the foliage, the trunks that yield the most juice; as the herdsman distinguishes, from the external signs, a good milch-cow. Amidst the great number of curious phenomena which I have observed in the course of my travels, I confess there are few that have made so powerful an impression on me as the aspect of the cow-tree. A few drops of vegetable juice recall to our minds all the powerfulness and the 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 negroes 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."

Mr. D. Lochart also visited the cow-trees in the Carccas, and drank of the milk from a tree which had a trunk seven feet in diameter, and measured one hundred feet from the root to the first branch. Sir R. K. Porter also paid them a visit, and his observations confirm those already recited. "The colour and consistency," he says, "were precisely those of animal milk, with a taste not less sweet and palatable; yet it left on the tongue a slight bitterness, and on the lips a considerable clamminess; an aromatic smell was most strongly perceptible when tasting it."

Other trees are known which possess similar properties to a greater or less extent. One of these is the "Tabayba dolce" of the Canaries (Euphorbia balsamifera). Here again we have a plant belonging to a different natural order from any of the others, namely, the Euphorbiaceæ, and one containing a large number of plants with acrid and purgative juices. Leopold von Buch states that the juice of this plant is similar to sweet milk, and, thickened into a jelly, is eaten as a delicacy.

A species of Cactus (C. mamillaris) also yields a milky juice equally sweet and wholesome. It now constitutes the type of a genus called Mamillaria. The milk is affirmed to be much inferior in its quality to the majority of the above.

It would scarcely be advisable for us to enter here upon the subject of the chemical composition of any of these vegetable juices, or to show their connection with those lactescent fluids which harden upon exposure, and then are known as india-rubber or caoutchouc. Although none of the cow-trees enumerated yield a true india-rubber, that substance, or one greatly resembling it, is afforded by some of their allies. It is curious to observe how, when failing to serve mankind in one direction, these trees become important servants in another. How forcibly this reminds us of the quaint lines of George Herbert—