AGRICULTURE AND PLANTING. 13 



O/i the Structure of Vegetables. 



copious nourishment. The young plant now begiu3 to rise to the surface of the 

 earth; the leaves unfold themselves, and, strengthened by the nourishment the 

 radicles supply, it pierces through the earth, and advances into the air, supplied 

 with every part in miniature; and the gradual increase and extension of those 

 parts, by the same vegetable energies, constitute the growth of plants. 



Plants that propagate their species by seeds, which, at a proper season, \x- . 

 getate, and produce young plants, are called oviparous. , 



Plants that send forth buds or radicles to be separated from the parent 

 plant at a proper period, and which then become perfect vegetables, are termed 

 viviparous. 



The chemical principles which vegetables take in as nourish- 

 ment, as yet known, are caloric or heat, light, electric matter, carbon, hydrogen 

 or inflammable air, oxygen or vital air, azote or mephitic air, and a very small por- 

 tion of phosphorus, sulphur, metals, and an earth. Plants inhale nourishment — 

 only in the forms of aqueous and gazeous solutiofis. The roots take in whatever 

 nourishment they receive — chiefly in water, and in gas mingled with water, and 

 other liquid solutions. The trdiik, branches, flowers, fruits, and leaves take in, 

 also, much aque6us nourishment; but receive a much larger proportioji of that 

 which they inhale, in a gazeous form: It is, in general, salutary for plants, to re- 

 ceive their nourishment, rather in a gazeous than in an aqueous form; because 

 what they take in the former way, is, for the most part, easier to be digested into 

 Avholesoine sap, than that which they imbibe in the latter state. Water unde- 

 composed, hydrogen, carbon, azote, oxygen, are the only sorts of food which 

 plants can take in. All soils, all airs, all situations, in which they grow and thrive, 

 must jafiord these elementary pabnla. Where these are to be obtained, in sufficient 

 quantity; plants take in, overall their surfaces, by the energy exerted in the epi- 

 dermis of the bark, — precisely that due proportion of each element, which is re- 

 quisite to their healthful support, according to the respective nature of every 

 different plant. D 



