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 dodonæa anguſtifolia, the climbing mimoſa (mimoſa ſcandens), and new kinds of the homæa.— 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.