Fortli-co'iaing Scientific Works. 205 



extensive benefits to the arts. It develops " colors for the dyer, 

 and materials for the weaver, and extracts healing juices, and salu- 

 tary poisons for the physician." But these points of utility are not 

 all. The subject rises to the higher contemplations of sublime phi- 

 losophy, displaying the wisdom and beneficence of the Creator, in 

 the disposition of elements and agencies regulated by unerring laws — 

 in a silent and unvarying process, sustaining and perfecting the veg- 

 etable world. A beautiful example of this occurs in the organiza- 

 tion of plants, and in the mode by which they receive their aliment. 

 The action of air, water, heat, and light, in sustaining arid promoting 

 their growth, is portrayed by this writer in the most lucid manner ; 

 after which an outline of their appHcation to agriculture is given, as 

 being one of the great ends of their creation. 



Water containing silex, soda, lime, carbonic acid, magnesia, and pot- 

 ash, absorbed by the roots, forms the ascending sap ; and after circula- 

 ting through every ramification of the plant, a portion of the water is 

 evaporated by the pores of the leaves, and the remaining part being 

 chemically converted into a liquid suited to its nourishment, returns 

 as descending sap, traversing every organ, and depositing in each 

 the materials requisite for its sustenance and growth. The evapora- 

 tion by the leaves is estimated at two thirds the quantity of water ab- 

 sorbed by the roots. 



As carbon is the base of the vegetable skeleton, so it is a principal 

 material of vegetable food ; and there is no law of nature more beau- 

 tiful than that which supplies it to the growing plant. The demand 

 of plants for carbon, is an obvious reason why manure is necessary 

 for the support of vegetation. It is essential that a thorough de- 

 composition should take place, resolving the materials into their 

 primitive elements ; for when not thus separated, the ingredients are 

 too gross to re-enter the vegetable system. Carbonic acid gas, be- 

 ing an abundant product of animal and vegetable decomposition, car- 

 bon is in this highly attenuated form conveyed by the water to the roots 

 of the plant, and by the atmosphere to its leaves. In its passage among 

 the leaves, the action of light decomposes the acid, occasioning the ox- 

 ygen to part from the carbon, which is then distributed by the descend- 

 ing sap, and appropriately deposited in the various organs of the plant. 

 Without the agency of the leaves in throwing off the oxygen, the 

 carbon would not be incorporated and assimilated in its solid form, 

 nor be deposited in sufficient quantity to perform so important a part. 

 The disintegration of rocks, however finely pulverized could not fur- 



