IV. ABSORPTION IN VEGETABLES. 93 



Faba.] Some have been deprived of their leaves; others 

 have been cut in two, and immersed by their stalks only : 

 these have been deprived of the extremity of the roots ; 

 those have been put into the liquid after the roots had 

 withered. Lastly, others were completely dried before 

 they were placed in (he fluid. 



By employing ferrocyanide of potassium as a test, we can 

 demonstrate the ascent of the ferruginous solution in the 

 interior of each of the plants, above the level of the liquid 

 in which they are immersed. 



We perceive, that in the living plant, furnished with 

 leaves and roots, the liquid has been considerably ele- 

 vated ; in those that were withered, and which have re- 

 covered their freshness in the aqueous solution, absorption 

 has been yet greater; while, lastly, it is most abundant 

 in those which had been previously deprived of their roots. 

 Whatever may be the liquid employed, it is always ab- 

 sorbed by the plant, except in the case of some acid alka- 

 line, or very concentrated saline solution, which by altering 

 and destroying the structure of the plant, and by coagulating 

 its juices, cannot be absorbed by it. 



Our best information on this subject is derived from 

 Saussure's celebrated work, entitled, Recherches Chimiques 

 sur la Vegetation. Here is a summary of it : 



1st. The roots absorb aqueous solutions of salts, but in 

 a much smaller proportion than water. 



2dly. Removal or alteration of the roots, and, in general, 

 every thing which lessens the force of vegetation, favours 

 the introduction of salts into the plant. 



3dly. A plant does not equally absorb all the salts con- 

 tained in the same solution. This is confirmed by the 

 fact, that certain salts are invariably met with in some 

 plants. Professor Piria has always found manganese in 

 the seeds of Lupinus a&us. 



