VEGETABLE ABSORPTION. 23 



being found to be more strongly impregnated 

 with the salts than before this absorption had 

 taken place. It would appear, however, that all 

 this is merely the result of a mechanical opera- 

 tion, and that it furnishes no evidence of any 

 discriminating faculty in the spongiole : for it is 

 found that, provided the material presented be 

 in a state of perfect solution and limpidity, it is 

 sucked in with equal avidity, whether its qualities 

 be deleterious or salubrious. Solutions of sul- 

 phate of copper, which is a deadly poison, are 

 absorbed in large quantities by the roots of plants, 

 which are immersed in them : and water which 

 drains from a bed of manure, and is consequently 

 loaded with carbonaceous particles, proves ex- 

 ceedinglyinjurious when admitted into the system 

 of the plant, from the excess of nutriment it con- 

 tains. But in the ordinary course of vegetation, 

 no danger can arise from this general power of 

 absorption, since the fluids which nature supplies 

 are always such as are suitable to the organs 

 that are to receive them. 



The fluid, which is taken up by the roots, and 

 which, as we have seen, consists chiefly of water, 

 holding in solution atmospheric air, together 

 with various saline and earthy ingredients neces- 

 sary for the nourishment of the plant, is in a 

 perfectly crude state. It rises in the stem of 

 the plant, undergoing scarcely any perceptible 

 change in its ascent; and is in this state conducted 



