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der was placed iu a phial containing pui* water, in 

 which a plant of peppermint was growing : the roots 

 of \he plant were pretty generally in contact with the 

 charcoal. The experiment was made in the beginning 

 of May, 1 805 ; the grwth of the plant was very vi- 

 gorous during a fortnight, when it was taken out of 

 the phial ; the roots were cut through in different 

 parts ; but no carbonaceous matter could be disco- 

 vered in them, nor were the smallest fibrils blackened 

 by charcoal, though this must have been the case had 

 the charcoal been absorbed in a solid form. 



No substance is more necessary to plants than 

 carbonaceous matter ; and if this cannot be introdu- 

 ced into the organs of plants except in a state of solu- 

 tion, there is every reason to suppose that other sub- 

 stances less essential will be in the same case. 



I found by some experiments made in 1 804, that 

 plants introduced into strong fresh solutions of sugar, 

 mucilage, tanning principle, jelly, and other substan- 

 ces died ; but that plants lived in the same solutions 

 after they had fermented. At that time, I supposed 

 that fermentation was necessary to prepare the food 

 of plants ; but I have since found that the deleterious 

 effect of the recent vegetable solutions was owing to 

 their being too concentrated ; in consequence of which 

 the vegetable organs were probably clogged with so- 

 lid matter, and the transpiration by the leaves pre- 

 vented. In the beginning of June, in the next year, 

 I used solutions of the same substances, but so much 

 diluted, that there was only about aio part of solid ve- 

 getable or animal matter in the solutions. Plants of 



