PROCEEDINOa OF THE FARMER^ ClUB. 189 



in driving the ascending sap through the proper vessels to the 

 leaves, and finally to its proper uses in the economy of the growth 

 of the plant, as well as the structure of the vessels themselves, 

 have been subjects of much inquiry and dispute; some thinking 

 that the spongioles are of the exact nature of a sponge, that they 

 therefore expand at the approach of moisture, and when surcharged 

 with it, contract and force it into the vessels of the fibrous roots, 

 thus acting as both suction and force pumps, by alternate dilata- 

 tion and contraction, and that the ascension of the sap to the leaves 

 is caused by capillary attraction; others by an invisible valvular 

 structure of the sap vessels, while still others attribute it to the 

 action of that mysterious agent, electricity, which, on account of its 

 occult nature, is made the scape-goat of modern miracle workers to 

 bear the sins of their too ready belief, out into the wilderness of 

 exploded humbugs — saying ' that the circulation of sap is carried 

 on by positive and negative electrical conditions, the laws of minus 

 and plus, or want and supply, which carries on the commerce of 

 the world.' 



" Probably the phenomenon in natural philosophy, discovered by 

 Dutrochet, to wit, the creation of an endosmose or inflowing, and 

 exosmose or outflowing current, by the juxtaposition of two fluids 

 of diflerent densities, separated by a porous septum, will explain 

 the absorption by the roots; while the following proposition of 

 Professor Draper will account for the passage of the sap through 

 the sap vessel to the leaves, when taken in connection with the 

 evaporization of a portion of the water by the leaves, to wit: ' If 

 the force of attraction of the particles of a solid for those of a 

 liquid exceeds half of the cohesive force of the latter for each 

 other, but is not equal to the whole force, the liquid will pass 

 through a pore of that solid substance, and in capillary tube of it, 

 will rise above its hydrostatic level.' But time and space will not 

 serve to pursue these curious and interesting investigations. I pro- 

 pose to do little more in this essay than to try to show where sap 

 comes from, where it goes to, and what becomes of it when it gets 

 there. The crude sap, then, after being absorbed b}^ the spongioles, 

 is conducted by the vasiform tissue of the fibrils to the vessels of 

 the main roots, and is then elevated to the leaves through the ducts 

 and fibres of the alburnum portion of sap wood of the stem of the 

 plant. On its way from the roots to the leaves, it is somewhat 

 modified by dissolving the previously formed secretions, which it 

 meets with on its way. In the leaves, it is converted into proper 



