No. 11. 



As^ricullural Address, 



353 



organs that, in their turn become developed, 

 to carry on the great function of nutrition 

 and growth. And it is tlie business of the 

 husbandman to acquaint himself with these 

 functions. 



Without going minutely into vegetable 

 physiology, it will be sufficient for our pre- 

 sent purpose to know that the elementary 

 te.xture of plants, consists of cells which 

 form the basis of all their organs ; tiiese 

 cells, as well as the spaces between them, 

 contain fluids of different kinds adapted to 

 fulfil different purposes in the vegetable 

 economy. Prior to the researches of mo- 

 dern chemistry it was supposed that pure wa- 

 ter alone, was sufficient to support vegeta- 

 tion, and many experiments were tried, which 

 resulted in favour of this opinion ; it was 

 not taken into the account, however, that 

 water contains a portion of atmospheric air, 

 and that the component parts of the atmos- 

 phere in its gaseous state, as well as in a 

 state of combination with water, were es- 

 sential to the growth and increase of vege 

 table matter. 



It is not water alone, nor any other agent 

 of itself, that is capable of fulfilling this im- 

 portant office. Heat, water, light, and air, 

 are all necessary to vegetable growth. Heat 

 is the cause of fluidity, without which the 

 sap cannot circulate. Water is the medium 

 through which nutriment is conveyed to the 

 plant; the air affords the principle of vital- 

 ity, while the light of the sun, by its attrac- 

 tive force is continually inviting the leaves 

 of plants to spread themselves to its influ- 

 ence, in order to facilitate their function of 

 exhalation. The extremities of the roots 

 serve the purpose of absorbing nourishment 

 from the soil, at which points, are placed lit- 

 tle spongioles, admirably qualified for the 

 task: and as the roots are constantly spread- 

 ing in all directions, they are always in con- 

 tact with some new portion of soil which 

 contains the appropriate food. It is believed 

 by some writers upon the subject, that there 

 exists a perfect uniformity in the direction 

 of the roots with the branches, so that a 

 great portion of the rain which falls from 

 the leaves of plants drops upon the earth at 

 a distance from the stem, corresponding with 

 the different extremities of the roots, and 

 that the spongioles receive a greater amount 

 of support than they would by a less careful 

 arrangement. As these little mouths are 

 incapable of imbibing thick fluids, nature 

 has supplied a solvent which is the mens- 

 truum of all the positive food of plants. 

 This, as we know, is rain. It receives in 

 its passage through the soil various ingredi- 

 ents, which it holds in solution, and in this 

 state is taken up by the roots, traverses the 



stem and branches of the plant without any 

 perceptible change in its quality, till it 

 reaches the leaves, and thus comes in contact 

 with the atmosphere, where it is subjected 

 to the process of exhalation. By this pro- 

 cess it parts with about two-thirds of its 

 water, and leaves the remainder more con- 

 centrated, and more divisible into the variety 

 of nutriment adapted to the different portions 

 of the plant. Before the leaves are Ibrmed, 

 the sap does not come so completely into con- 

 tact with the external air. It is not neces- 

 sary that it should. Its office being the sus- 

 tenance of an incomplete organism, it has 

 been called the nursling sap. By this pro- 

 cess of exhalation, the oxygen contained in 

 the water which is separated, is thrown into 

 the atmosphere in the form of gas, and its 

 carbon retained, which being one of the 

 principal ingredients of vegetable structures 

 is returned to the vegetable system for its 

 support. It is in this function, as has been 

 stated, that light exercises its peculiar power 

 over vegetation ; for during the night this 

 process of respiration is partially suspended, 

 and a portion of oxygen, the great purifier 

 of organic existence, is admitted, to vitalize 

 the fluids of the plant, and on the return of 

 daylight is again dissipated, to combine with 

 the air. From the returning sap, as it cir- 

 culates through the plant, is taken up differ- 

 ent substances and deposited in its different 

 parts by another set of organs, which in the 

 economy of nature's laws have been provided 

 for the purpose, and whose particular office 

 has been termed secretion. Wax, honey, 

 starch, the turpentines, resins, balsams, are 

 familiar examples of vegetable secretion. 

 So also, are considered the bitter, aromatic, 

 narcotic, and acrid juices, which impart to 

 vegetables their peculiar taste and odor. 



The excretion of plants consists in their 

 freeing themselves of noxious or useless par- 

 ticles which they may have absorbed w^ith 

 their nourishment; and the fact that plants 

 possess this power, is of great importance to 

 the farmer, inasmuch as it explains to him 

 the advantage of a rotation of crops; for 

 though materials may have been thrown off 

 by one plant as injurious to it, it does not 

 follow that others of a different species will 

 reject them ; they may afford to another va- 

 riety nourishment, exactly such as is need- 

 ful for their growth. This may account for 

 the fact which has been remarked for many 

 years in this county, and no doubt in other 

 peach growing districts, that a crop of fine 

 fruit cannot be procured from an orchard 

 immediately succeeding another, on the 

 same ground. The excretions of the peach 

 tree have impregnated the soil with quali- 

 ties that are obnoxious to its growth, and 



