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LV. Chim'ical Researches on Fegetat'wn. By Theodohe 

 DK Saussuhe. Ah Extract read in the French National 

 Institute iij L. BeutholleT *. 



-L HE class charged me to give a verbal account of a work 

 presented to it bv Theodore de Saussure, entitled liecherches 

 Chimiqnes siir la J'cgetalion ; but the important results of 

 these researches have induced me to present to it an extract 

 which may enable it to judije of the progress for which the 

 theory of vegetation is indebted to this author. 



Senebier, whose name occurs so often in the history of 

 the phvsiology of vegetables, Gough, Rollo, and Wood- 

 house/had observed that seeds could not germinate without 

 tlic contact of oxvgen gas, and that germination is accom- 

 panied by a production of carbonic acid. Saussurc men- 

 tions the experiments he before published, and which, in- 

 deed, prove that in this effect the volume of the oxygen gas 

 is not altered, but that it is onlv changed into carbonic acidj 

 v>hencc it results, that in germination a seed loses a part of 

 its carbon, bv means of the oxygen gas which combines with 

 it retaining the elastic state. 



If the Seed which has germinated be afterwards dried, it 

 is found that it loses a weight very much superior to that 

 which arises from the extraction of the carbon ; whence 

 Saussurc concludes that there is separated also during the 

 desiccation watcr^ or a, corresponding proportion of hydro- 

 gen and oxvgen, which greatly surpasses the weight of thu 

 carboii which has been disengaged : a consequence of this 

 observation is, that notwithstanding the loss of the carbon 

 it experiences in forming carbonic acid, the seed which has 

 imdergone desiccation after germination is found to have a 

 greater proportion of that element th.ii if if had been dried 

 eforc it e)^|)eneneed germination. 



The carbonic acid iras, which is a product of germina- 

 tion, becomes itself an obstacle to its progress ; so that, it 

 carbonic acid be mixed with the air which is in contact 

 with the seed, the germination is rendered more feeble than 

 by a similar mixture of azotic gas or hvtirogen gas. 



Water charged with carbonic acid is equally contrary to 

 the development (jf the seeds put to e;erminate in it j but, if 

 they have passed the period of germination and attained to 

 that where vegetation begins, the carbonic acid bcomes an 

 ■useful agent, underconditions wliich, as they have not yet 



• I'rom Anntila ile Cljimic, No. 150. 



\J 2 been 



I 



