240 THE FLUID COMPONENTS OF PLANTS. 



in the vessels of the inner bark that the greatest activity, 

 irritability, and degree of vital energy reside, :f that part 

 be wounded to any considerable extent, so that the 

 external air finds access to it, exfoliation, and the death 

 of the part, and sometimes that of the whole plant, 

 follow. 



Such are the principal solid components of the veg- 

 etable body. Other solid matters also enter into their 

 structure ; but, as they are not common to the vege- 

 table race, they cannot be ranked in the general com- 

 position. Perhaps, indeed, all the parts which have 

 been examined may be resolved into modifications of 

 the membranous and cellular textures ; but, although 

 we allow that the vessels, ligneous fibre, glands, and 

 epidermis most probably are composed of membra- 

 nous, or cellular tissue, differently modified, yet as 

 each of these parts possesses very distinct functions, 

 such a refinement could only perplex and bias the 

 observer in search of the truth. 



II. General Fluid Components of Plants. 



Vegetables, by their vital energy, develope them- 

 selves, increase in bulk, and augment the quantity of 

 solid matter they contain, consequently the principles 

 of the solids must be contained in the particular fluids 

 which they select and imbibe from the soil ; but in 

 what manner the fluids are changed into solids, and 

 whether any of the solid matters be taken up ready 

 formed, or whether they result from a transformation 

 effected solely by the action of the vegetable vessels, 

 are subjects of consideration upon which it would be 

 premature to enter. These fluids, however, after be- 

 ing absorbed by the roots, enter into and fill the cells 

 and vessels of the plant, and form a very considera- 

 ble portion of the bulk of the vegetable body. A? 



