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|Spaltenumbruch|
GERMINATION, among botaniſts, is a very in-tereſting ſubject on which the late diſcoveries in che-miſtry have thrown much light ſince the article Ger-mination was publiſhed in the Encyclopædia. In theyear 1793, Mr Humboldt diſcovered, that ſimple me-tallic ſubſtances are unfavourable to the germination ofplants, and that metallic oxyds favour it in proportionto their degree of oxydation. This diſcovery inducedhim to ſearch for a ſubſtance with which oxygen mightbe ſo weakly combined as to be eaſily ſeparated, andhe made choice of oxygenated muriatic acid gas mix-ed with water. Creſſes (lepidium ſativum) in theoxygenated muriatic acid ſhewed germs at the end ofſix hours, and in common water at the end of 32 hours.The action of the firſt fluid on the vegetable fibres isannounced by an enormous quantity of air bubbleswhich cover the ſeeds, a phenomenon not exhibitedby water till at the end of from 30 to 45 minutes.Theſe experiments announced in Humboldt’s FloraSubterranea Fribergenſis, and in his Aphoriſms on thechemical phyſiology of Plants, have been repeated byothers . They were made at a temperature of from12 to 15 Reaumur. In the ſummer of 1796, Hum-boldt began a new ſeries of experiments, and foundthat by joining the ſtimulus of caloric to that of oxy-gen he was enabled ſtill more to accelerate the pro-greſs of vegetation. He took the ſeeds of gardencreſſes (lepidium ſativum), peas, (piſum ſativum), Frenchbeans (phaſeolus vulgaris), garden lettuce (lactuca ſati-va), mignonette (reſeda odorata); equal quantities ofwhich were thrown into pure water and the oxygena-ted muriatic acid at a temperature of 88° F. Creſſesexhibited germs in three hours in the oxygenated mu-riatic acid, while none were ſeen in water till the endof 26 hours. In the muriatic, nitric , or ſulphuricacid, pure or mixed with water, there was no germ atall: the oxygen ſeemed there to be too intimately unit-ed with baſes of azot or ſulphur, to be diſengaged bythe affinities preſented by the fibres of the vegetable.The author announces, that his diſcoveries may oneday be of great benefit in the cultivation of plants.His experiments have been repeated with great induſ-try and zeal by ſeveral diſtinguiſhed philoſophers. Pro-feſſor Pohl at Dreſden cauſed to germinate in oxyge-nated muriatic acid the ſeed of a new kind of euphorbia
taken from Bocconi’s collection of dried plants, 110 or120 years old. Jacquin and
Van der Schott at Vienna
threw into oxygenated muriatic acid all the old ſeedswhich had been kept 20 or 30 years at the botanicalgarden, every attempt to produce vegetation in whichhad been fruitleſs, and the greater part of them were
|Spaltenumbruch| ſtimulated with ſucceſs. Even the hardeſt ſeeds yield-ed to this agent. Among thoſe which germinatedwere the yellow bonduc or nickar tree (guilandinabonduc), the pigeon cytiſus or pigeon pea (cytiſus ca-jan), the dodonæa anguſtifolia, the climbing mimoſa (mi-moſa ſcandens), and new kinds of the homæa.—Thereare now ſhewn at Vienna very valuable plants whichare entirely owing to the oxygenated muriatic acid,and which are at preſent from five to eight inches inheight. Humboldt cauſed to germinate the cluſia ro-ſea, the ſeeds of which had been brought from the Ba-hama iſlands by Booſe, and which before had reſiſtedevery effort to make them vegetate. For this pur-poſe he employed a new proceſs, which ſeems likely tobe much eaſier for gardeners who have not an oppor-tunity of procuring oxygenated muriatic acid: Heformed a paſte by mixing the ſeeds with the blackoxyd of manganeſe, and then poured over it the mu-riatic acid diluted with water. Three cubic inches ofwater were mixed with half a cubic inch of the mu-riatic acid. The veſſel which contains this mixturemuſt be covered, but not cloſely ſhut; elſe it mightreadily burſt. At the temperature of 95° the muria-tic acid becomes ſtrongly oxydated; the oxygenatedmuriatic gas which is diſengaged paſſes through theſeeds; and it is during this paſſage that irritation of thevegetable fibres takes place.—Philoſophical Magazine.
