Page:Popular Science Monthly Volume 15.djvu/663

Rh on the fecundation of the vanilla at the Museum; and in a prize essay by H. Baillon the same fact is confirmed. "When the sky was overcast," he writes, "and the temperature rather low, I had to penetrate into the stigmatic antrum, in order there to place the little pollen apparatus; but, after the sun had made pretty warm the greenhouse in which the plant was suspended, then, provided the contents of the anther were not firmly attached to the top of the pins on which they were borne, they would become detached from it on being brought within a certain distance from the stigma, and, being strongly attracted, would shoot like an arrow into the cavity." This curious observation appears to be without precedent save in this plant; it is certainly of a character to interest the physiologist.

Darwin has observed a strange movement of the pollinia in the flowers of Catasetum, which, under the influence of innervation, "were shot forth to the distance of two or three feet"; but here the phenomenon is purely mechanical.

The first travelers who observed the vanilla in the wild state have asserted that it grows in low, moist situations near the seacoast; but in later times it has been found in the forests, and is known to occur in divers parts in Central America.

The number of species of the vanilla-plant is not clearly determined. Of types cultivated in Mexico there are twelve, and of these five are reckoned as distinct species. One of these species, the Vanilla lec, embraces six varieties. Delteil gives a list of species cultivated in different countries; it is as follows: In Mexico, Vanilla sativa, V. silvestris, V. planifolia, and V. pompona; in Guiana, V. guianensis, with yellow flowers and large fruit; at Bahia, V. palmarum; in Brazil and Peru, Linné's V. aromatica, which possesses less fragrance than the others. In Réunion two sorts are cultivated, both of them apparently varieties of V. planifolia.

Under the title of vanillon is found in commerce a short, thick vanilla-pod, produced by V. pompona, the fruit of which is of far less value than that of the V. planifolia.

Now that the cultivation of vanilla is widely extended, the fine quality of beans can be had at from one hundred and eighty to two hundred and fifty francs per kilogramme. But when it is "frosted," i. e., covered with needles of vanillin, it may fetch a higher price. Vanillon is worth about one fourth as much as vanilla.

Vanilla plantations, to be profitable, require great and constant care. The plants are multiplied by cuttings. The cuttings should bear three or four leaves, and may be a metre or over in length. Rainy and hot seasons are chosen by preference for planting. The cuttings must be planted in rows apart, in a soil rich in vegetable molds fertilized with the decaying leaves and branches of plants, especially of the banana. Each cutting should have a prop, and the ground at its root is to be kept moist by a heap of stones around the stem.