JO 



find one set of small vessels, running from the roots to tLe ex- 

 tremities, through which the sap ascends, while in its progress 

 it is undergoing those changes that will fit it for becoming a part 

 of the vegetable. These vessels resemble the arteries in the 

 animal system. When the sap is thus conveyed to the heaves and 

 other extremities of the plant, it there comes in contact with the 

 atmosphere, gives otf its redundancies, ar;d absorbs water, and 

 perhaps other principles, essential lo the health of the plant.* 

 The leaves of plants, therefore, perform nearly the same functions 

 as the lungs of anima;s. A second set of vessels, exterior to the 

 first and mostly confined to the bark, now conveys the food of the 

 plant, thus prepared, to every part that needs nouri-shment; even 

 to the very roots from which it proceeded. These vessels cor- 

 respond to the veins. Other vessels are found in plants, corres- 

 ponding, probably, to those similarly situated in the animal sys- 

 tem ; yet too complicated for explanation on this occasion. Suf- 

 fice it to mention, that in the vegetable, as well as animal econo- 

 my, we find the principle of life — itself inscrutable — tnodifymg and 

 controlling every operation and keeping the wonderful machine- 

 ry in ceasless play. 



So much for the botany, or rather anatomy, of the vegetable 

 kingdom. We next enquire what are the simple substances that 

 enter into the composition of plants; for until the agriculturist 

 knows this, how shall he ascertain what materials are best adapt- 

 ed to their nourishment ? And Chemistry stands ready to 

 answer the enquiry. Out of the fifty simple substances or 



* It has been the general opinion of botanists and chemists, that the leaves 

 of plants absorb, from the attnospheie. Carbonic acid; or that gas called 

 chnak (lamp, found in wells and caverns, so falal to animal life ; and in thin 

 way they have supposed the a1m(»sphere is purified. But the recent experi- 

 ments of Mr. Ellis, a distinguished vegetable physiologist, have thrown so 

 much doubt on this beautiful theory, that I did not fnel justified in stating 

 positively that the leaves of vegetables possess the power of absorbing thia 

 gas. Mr. Ellis suppose* that the only use of the oxygen of the atmosphere 

 is to convert the superabundant carbon, given off by tlie leaves of plants, in- 

 to carbonic acid ; exactly in the same manner as this is done by the respira- 

 tion of animals. So far as agriculture is concerned, however, it seems of 

 little importance in what way these points are determined : since it is agreed 

 on all hands, that the pure air of the atinosphere should come in contact with 

 the leaves of plants. Soe Edinburgh Encyclopedia Article Botawt. p. 57, 

 58. 



