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|Spaltenumbruch|
Germination,
chemical experiments respecting. Thelate diſcoveries in chemiſtry, have thrown much light onthis ſubject. In 1793, M. Humboldt diſcovered, thatſimple metallic ſubſtances are not favourable to the germi-nation of plants, but that metallic oxyds favour it in pro-portion to their degree of oxidation. This led him toſearch for a ſubſtance with which oxygene might be ſoweakly combined as to be eaſily ſeparated, and he triedoxygenated muriatic acid gas mixed with water. Creſſes(See Lepidium), in this acid ſhewed germs at the end offix hours, and in common water at the end of 32 hours.The action of the acid on the vegetable fibres was an-nounced by a great number of air-bubbles covering theſeeds, which did not take place with water till the endof 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 beenrepeated by Meſſrs. Uſlar, Plenck, Villdenow and others.See Dictionaire de Physique, par
Gehler
. They weremade at a temperature of from 12 to 15 of Reaumur. In1796, Humboldt made ſome new experiments, and foundthat, by joining caloric to oxygen, vegetation was ſtillmore accelerated. He threw equal quantities of the ſeedsof garden creſſes into pure water and oxygenated muriaticacid, at a temperature of 58° F. Creſſes germinated inthe acid in three hours, but in the water not till the endof 26 hours. In the muriatic, nitric or ſulphuric acid,there was no germ at all: though according to the expe-riments of M. Candolle, the nitric acid accelerates germi-nation 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 takenfrom Bocconni’s collection of dried plants, 110 or 120years old. Jacquin and
Van der Schott at Vienna threwinto oxygenated muriatic acid all the old ſeeds, which hadbeen kept 20 or 30 years at the botanical garden, everyattempt to produce vegetation in which had proved fruit-leſſ, and the greater part of them, even the hardeſt ſeedsgerminated. Among theſe were the yellow bonduc, ornickar tree, (See Guilandina,) the pigeon pea, (See
Cytisus,) the Dodonæa Angustifolia, the climbing mimo-ſa, (See Mimosa), and ſome new ſpecies of the
Homæa.
There are not ſhewn at Vienna any valuable plants, whichare entirely raiſed by the oxygenated muriatic acid, and
|Spaltenumbruch| are from five to eight inches high. Humboldt made the
clusia rosea to germinate, the ſeeds of which had beenbrought from the Bahama iſlands by Booſe, and had re-ſiſted every previous effort to make them vegetate. Forthis purpoſe he uſed a new proceſſ, which will be eaſier forgardeners who cannot procure the oxygenated muriaticacid. He formed a paſte by mixing the ſeeds with theblack oxyd of manganeſe, and then poured over it the mu-riatic acid diluted with water, in the proportion of half acubic inch of the acid to three of water. The veſſel con-taining this mixture muſt be covered, but not ſhut cloſe,leſt it ſhould burſt. At the temperature of 95°, the mu-riatic acid becomes ſtrongly oxydated; the oxygenatedmuriatic gas which is diſengaged paſſes through the ſeeds;and during this paſſage the irritation of the vegetable fibrestakes place. Philos. Mag.
