Germination, chemical experiments respecting.

The late diſcoveries in chemiſtry, have thrown much light on this ſubject.

In 1793, M. Humboldt diſcovered, that ſimple metallic ſubſtances are not favourable to the germination of plants, but that metallic oxyds favour it in proportion to their degree of oxidation.

This led him to ſearch for a ſubſtance with which oxygen might be ſo weakly combined as to be eaſily ſeparated, and he tried oxygenated muriatic acid gas mixed with water. Creſſes (See Lepidium, N° 2.) in this acid ſhewed germs at the end of 6 hours, and in common water at the end of 32 hours.

The action of the acid on the vegetable ſibres was announced by a great number of airbubbles covering the ſeeds, which did not take place with water till the end of from 30 to 45 min.

Theſe experiments, publiſhed in Humboldt’s Flora Subterranea Fribergenſis, and in his Aphoriſms on the Chemical Phyſiology of Plants, have been repeated by Meſſrs Uſlar, Plenck, Villdenow and others.

See Dictionaire de Phyſique, par Gehler.

They were made at a temperature of from 12 to 15 of Reaumur.

In 1796, Humboldt made ſome new experiments, and found that, by joining caloric to oxygen, vegetation was ſtill more accelerated.

He threw equal quantities of the ſeeds of garden creſſes into pure water and oxygenated muriatic acid, at a temperature of 58° F. Creſſes germinated in the acid in 3 hours, but in the water not till the end of 26 hours.

In the muriatic, nitric, or ſulphuric acid, there was no germ at all: though, according to the experiments of M. Candolle, the nitric acid accelerates germination alſo, when greatly diluted with water.

Prof. Pohl at Dreſden cauſed the ſeed of a new ſpecies of Euphorbia to germinate in oxygenated muriatic acid, though 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 proved fruitleſs, and the greater part of them, even the hardeſt ſeeds, germinated.

Among theſe were the yellow bonduc, or nickar tree, (See Guilandina, N° 1.) the pigeon pea, (See Cytisus, N° 2.) the Dodonæa Anguſtifolia, the climbing mimoſa, (See Mimosa, N° 19.) and ſome new ſpecies of the Homæa . There are now ſhewn at Vienna very valuable plants, which are entirely raiſed by the oxygenated muriatic acid, and are from 5 to 8 inches high.

Humboldt made the cluſia roſea to germinate, the ſeeds of which had been brought from the Bahama iſlands by Booſe, and had reſiſted every previous effort to make them vegetate.

For this purpose he uſed a new proceſs, which will be eaſier for gardeners who cannot procure the oxygenated muriatic acid.

He formed a paſte by mixing the ſeeds with the black oxide of manganeſe, and then poured over it the muriatic acid diluted with water, in the proportion of half a cubic inch of the acid to 3 of water.

The veſſel containing this mixture muſt be covered, but not ſhut cloſe, leſt it ſhould burſt.

At the temperature of 95°, the muriatic acid becomes ſtrongly oxydated; the oxygenated muriatic gas which is diſengaged paſſes through the ſeeds; and during this paſſage the irritation of the vegetable fibres takes place. Philoſ. Mag.