GERMINATION

GERMINATION, among botanists, is a very interesting subject, on which the late discoveries in chemistry have thrown much light since the article GERMINATION was published in the Encyclopaedia. In the year 1793, Mr Humboldt discovered, that simple metallic substances are unfavourable to the germination of plants, and that metallic oxides favour it in proportion to their degree of oxydation. This discovery induced him to search for a substance with which oxygen might be so weakly combined as to be easily separated, and he made choice of oxygenated muriatic acid gas mixed with water. Cresses (lepidium sativum) in the oxygenated muriatic acid shewed germs at the end of six hours, and in common water at the end of 32 hours. The action of the first fluid on the vegetable fibres is announced by an enormous quantity of air bubbles which cover the seeds, a phenomenon not exhibited by water till at the end of from 30 to 45 minutes. These experiments announced in Humboldt's Flora Subterranea Friburgensis, and in his Aphorisms on the chemical physiology of Plants, have been repeated by others (A). They were made at a temperature of from 12 to 15 Reaumur. In the summer of 1796, Humboldt began a new series of experiments, and found that by joining the stimulus of caloric to that of oxygen he was enabled still more to accelerate the progress of vegetation. He took the seeds of garden cresses (lepidium sativum), peas, (pisum sativum), French beans (phaseolus vulgaris), garden lettuce (lactuca sativa), mignonette (reseda odorata); equal quantities of which were thrown into pure water and the oxygenated muriatic acid at a temperature of 88° F. Cresses exhibited germs in three hours in the oxygenated muriatic acid, while none were seen in water till the end of 26 hours. In the muriatic, nitric (B), or sulphuric acid, pure or mixed with water, there was no germ at all: the oxygen seemed there to be too intimately united with bales of azot or sulphur, to be disengaged by the affinities presented by the fibres of the vegetable. The author announces, that his discoveries may one day be of great benefit in the cultivation of plants. His experiments have been repeated with great industry and zeal by several distinguished philosophers. Professor Pohl at Dresden caused to germinate in oxygenated muriatic acid the seed of a new kind of euphorbia taken from Bocconi's collection of dried plants, 110 or 120 years old. Jacquin and Vander Schott at Vienna threw into oxygenated muriatic acid all the old seeds which had been kept 20 or 30 years at the botanical garden, every attempt to produce vegetation in which had

had been fruitless, and the greater part of them were stimulated with success. Even the hardest seeds yielded to this agent. Among those which germinated were the yellow bonduc or nickar tree (guilandina bonduc), the pigeon cytius or pigeon pea (cytius cajan), the nedonza angustifolia, the climbing mimosa (mimosa scandens), and new kinds of the bonnea.—There are now shewn at Vienna very valuable plants which are entirely owing to the oxygenated muriatic acid, and which are at present from five to eight inches in height. Humboldt caused to germinate the clusia rosea, the seeds of which had been brought from the Bahama islands by Boose, and which before had resisted every effort to make them vegetate. For this purpose he employed a new process, which seems likely to be much easier for gardeners who have not an opportunity of procuring oxygenated muriatic acid: He formed a paste by mixing the seeds with the black oxyd of manganese, and then poured over it the muriatic acid diluted with water. Three cubic inches of water were mixed with half a cubic inch of the muriatic acid. The vessel which contains this mixture must be covered, but not closely shut; else it might readily burst. At the temperature of 95° the muriatic acid becomes strongly oxydated; the oxygenated muriatic gas which is disengaged passes through the seeds; and it is during this passage that irritation of the vegetable fibres takes place.—Philosophical Magazine.

GESCHE or AUBA, or GIZ GIZ, a species of grass growing plentifully near Rat el Fez on the borders of Abyssinia. It begins, says Mr Bruce, to shoot in the end of April, when it first feels the humidity of the air. It advances then speedily to its full height, which is about 3 feet 4 inches. It is ripe in the beginning of May, and decays, if not destroyed by fire, very soon afterwards.

The leaf is long, pointed, narrow, and of a feeble texture. The stock from which it shoots produces leaves in great abundance, which soon turn yellow and fall to the ground. The goats, the only cattle these miserable people have, are very fond of it, and for it abandon all other food while it is within their reach. On the leaves of some plants our author saw a very small glutinous juice, like to what we see upon the leaves of the lime or the plane, but in much less quantity; this is of the taste of sugar.

From the root of the branch arises a number of stalks, sometimes two, but never, as far as he had seen, more than three. The flower and feed are defended by a wonderful perfection and quantity of small parts. The head when in its maturity is of a purplish brown.

This species of grass was one of the acquisitions of our author's travels. It was not before known in Europe, nor when he published his book had the feed produced a plant any where but in the garden of the French king.