On the Effects of Oxygen in accelerating Germination.

From the Journal de Physique, 1798.

Mr. Humboldt discovered, in 1793, that simple metallic substances are unfavourable to the germination of plants, and that metallic oxydes 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 showed 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 Fribergensis, and in his Aphorisms on the chemical physiology of Plants, have been repeated by others.

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 or sulphuric acid, pure or mixed with water, there was no germ at all: the oxygen seemed there to be too intimately united with bases 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 Van der 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 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 cytisus or pigeon pea (cytisus cajan), the dodonaea angustifolia, the climbing mimosa (mimosa scandens), and new kinds of the homaea.-- There are now shown 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 the oxygenated muriatic acid: He formed a paste by mixing the seeds with the black oxyde 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 oxygenated; 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.

See Uslar's Fragments of Phythology, Plenck's Physiology , Villdenow's Dendrology, and Dictionnaire de Physique par Gehler.

The nitric acid, however, diluted with a great deal of water, accelerates germination also, according to the experiments of Candolle, a young naturalist, who has applied with great success to vegetable physiology.

This phenomenon is the more interesting, as chemistry affords other analogies of the oxygenated muriatic acid and the nitric acid.

Professor Pfaff , at Kiel, by pursuing Humboldt's experiments, has found that frogs suffocated in oxygenated muriatic acid gas increase in irritability, while those which perish in carbonic acid gas are less sensible of Galvanism.