LECT. III.] THE SAP. 103 



GENERAL FLUID COMPONENTS. 



Vegetables, by their vital energy, 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 trans- 

 formation effected solely by the action of the 

 vegetable vessels ; are subjects of consideration 

 upon which, in the present stage of our inquiries, 

 it would be premature to enter. These fluids, 

 however, after being absorbed by the roots, enter 

 into and fill the cells and vessels of the plant, 

 and form a very considerable portion of the bulk 

 of the vegetable body. As soon as they enter the 

 plant, they constitute its SAP, or common juice, 

 to the nature of which, as it is one of the general 

 components of vegetables, we must now direct 

 our attention. 



Were we about to examine the moving powers 

 by which the fluids selected from the soil, and 

 absorbed by the roots of plants, are carried for- 

 ward through the vessels, we would demonstrate 

 that although these moving powers operate at all 

 times during the life of the vegetable, yet, that 



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