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XII. Memoir on the Degree of Selection exercised by Plants, with regard to 
the Earthy Constituents presented to their Absorbing Surfaces, By CHARLES 
Dauseny, M.D., F.R.S. L.S. G.S., &c., Professor of Botany and Chemistry 
in the University of Oxford. 
Read November 19th, and December 3rd, 1833. 
AMONGST the subjects recommended for consideration by the Chemical 
Sub-committee of the British Association for the Advancement of Science, 
during their Meeting at York in 1831, was that of the sources from which 
organic bodies derive their fixed principles; and as it was known to some of 
my friends that I had been engaged in certain inquiries that bore upon this 
subject, a request that I would undertake the investigation was accordingly 
entered upon the Minutes. I obtained, therefore, from this circumstance an 
additional motive for endeavouring, so far as my opportunities allowed, to 
prosecute the train of experiments which I had begun; and if I should scarcely 
yet have succeeded in determining to my entire satisfaction, whether or no 
there be any foundation for the idea sometimes entertained, that the earthy 
and alkaline principles which organized and living bodies contain are in any 
case elaborated by themselves, the reason must be sought for rather in the 
intricacy of the subject than in any want of disposition on my part to carry 
on an inquiry so recommended. 
Incidentally, however, the results of my researches seem to lead to the 
establishment of a fact, which, as it serves to modify one of the conclusions 
deduced by the younger Saussure from his experiments on vegetation*, de- 
serves, perhaps, a brief notice; and it is on this account, rather than for the sake 
of any new light I may have been able to throw upon the principal point in 
question, that I am desirous of laying before the Society the following details. 
In the experiments that were made by Braconnot-+, Schraderf, and others, 
* Recherches Chimiques sur la Végétation, 1804. T Annales de Chimie, vol, lxi. p. 137. 
i Gehlen's Journal, vol. v. p. 255. 
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