VEGETATION. 



The rays of light, likewife, appear to contribute to ftimu- 

 latc plants, with the various gafes or vapours they abforb 

 and take up from the air. 



Pure air has alfo been found by many to be effential to 

 the produftion of perfeft feeds, pulfe, grain, and fruit, and 

 that by its aftion upon or being taken up by the foil, it has 

 very powerful and beneficial effefts in promoting vegetation 

 and the perfedl growth of plants and crops. 



Thus water, air, and thefe other matters, appear to have 

 a very great Ihare in the vegetation and nourifhment of ve- 

 getables, but efpecially the two former. The firfl has been 

 confidered as indifpenfably neceflary to the procefs, and as 

 fiipplying the principal materials of vegetable juices. It is 

 unqueftionably the chief medium through which the various 

 nutritious matter derived from the foil, is conveyed to the 

 plants which grow upon it. But it has been fuppofed more 

 favourable to the vegetation and growth of grafs plants or 

 crops than thofe of the grain kind ; as crops of graffes may 

 be continually produced by watering, while with thofe of 

 grain it has been found to be wholly impoffible. It is 

 found, however, that foft water, fuch as that of rivers, 

 rain, or which has been expofed to the aftion of the fun for 

 fome time, is more favourable to vegetation, than fuch as is 

 hard, as that of fprings, or which is impregnated with me- 

 taUic fubftances and other fuch matters. The author of 

 Phytologia confidcrs the firft three things neceflary to the 

 infant vegetation and growth of plants to be heat, water, 

 and air, as furnifhing the general caufe of fluidity, the 

 menttruum in which nutriment is conveyed, and the prin- 

 ciple of excitabihty fo perpetually neceflary to all organic 

 life. 



However, befides thefe different matters, other agents 

 are neceflary, after the plants have been formed and evolved, 

 to the perfeft vegetation and growth of the crops, as thofe 

 of earth or other fuch matters, which are not only ufeful and 

 eflential for the purpofe of holding and fupporting the 

 plants in a fteady and ereft manner, but alfo for containing 

 and conveying, at leaft, fome portion of the food on which 

 they live, as derived from the atmofphere or other fources, 

 and for the regular ramification and extenfion of their fibrous 

 roots, in order that it may be more certainly provided and 

 fupplied. They are beneficial too in receiving, retaining, and 

 diftribuling moift;ure to them, as well as in receiving, re- 

 flefting, and difperfing the heat of the fun, dews, and ex- 

 halations of different kinds, by which their growth and 

 perfeftion are greatly promoted. For though fome plants 

 of the aquatic kind grow in water, moft of them have 

 their roots in earth. Even marine plants, although they 

 grow upon bare rocks or ftones, are well known to be 

 fixed to them, and that they derive their food from the fea- 

 water in or near which they exift. It has been contended 

 by fome, that plants are aftually nourifhed by earth alone, 

 but numerous experiments fliew the opinion to be erroneous, 

 and that it is perhaps only the medium of their exiftence. 

 It is well afcertained that they are capable of acquiring a 

 great acceffion of weight, without almofl: any lofs of weight 

 of the earth in which they have been planted. 



The aid and affiftance of dead organized materials are, 

 likewife, requifite in the procefs of vegetation and the 

 growth of crops, as it would feem to "be a part of the beau- 

 tiful and orderly arrangement of Nature, that nothing fliould 

 have life in vain, and that the deftruftion of one plant or 

 animal fliould furnifli food for others : confequently, that 

 however ufeful air, water, light, heat, and earth may be to 

 the growth of plants and crops, it is, if not certain, at leaft 

 queftionable, it is thought, whether they could ever come 

 to perfeftion without the help of matter that had been for- 



merly in an organized ftate. The richeft; foils, it is well 

 known, are full of dead animal and vegetable matter, and 

 there is no foil that will not produce plants or crops if a 

 fufficient quantity of dead animal or vegetable fubftance 

 be added to it. Under this denomination are comprehended 

 all thofe manures which are found fo ufeful in cultivation, 

 more efpecially thofe to which fome authors give the name 

 of mucilaginous, enriching, or tiutritious. Thefe fubftances 

 and materials are greatly beneficial, by correfting the tena- 

 city of ftiff foils or lands, and the over-porofity of light ones, 

 by producing a fermentation in them, and by affording nu- 

 tritive matter to the roots of vegetables, as well as by re- 

 taining moifture in dry and expelling it in wet lands. Saline 

 fubftances have been fuppofed too of much importance in 

 vegetation by fome, but they do not appear effential to the 

 growth of any fort of plants except the marine ; and there 

 are many produftive foils in which little or no faline matter 

 can be difcovered. Such matters may, however, be of ufe 

 to vegetation, though not effential to it. That of common 

 fait may operate upon plants as it does upon the human 

 body, by affifting to digeft the food, without furnifhing nu- 

 triment itfelf. It is of ufe, mixed with dung, as an afliftant 

 to putrefaftion, and it may aft in the fame way in promot- 

 ing vegetation. It is ferviceable too by attrafting moifture, 

 dellroying vermin in the foil, and decayi>ig and reducing 

 the roots of any plants it may firft meet with, thus furnifh- 

 ing nourifhment to the fucceeding ones. 



It is found hkewife, that the culture of the earth is effen- 

 tially neceffary for the vegetation and growth of plants and 

 crops to perfeftion, the health and vigour of both the roots 

 and branches being thereby greatly increafed. By dividing 

 and reducing the particles of foils, the roots of the plants 

 and crops put into them can more eafily and readily pene- 

 trate and fpread out in them, as well as fuck in more expe- 

 ditioufly the nourifliment which they contain. By proper 

 and effeftual culture too, fuch weeds or ufelefs plants as are 

 apt to rife, are extirpated and deftroyed, whilft ftirring the 

 earth admits air and moifture more fully to the foils, and 

 to thofe plants and crops the feeds or fets of which have 

 been fown or put in them. It is evident likewife, that 

 young trees thrive and fucceed much better, if the foils in 

 which they are planted have been previoufly ploughed in fo 

 deep a manner, as readily to admit their roots and fuckers. 

 Even after they are planted, it is fuppofed to be of great 

 fervice to have potatoes and other fuch roots cultivated 

 among the young trees in the plantations with a view to kill 

 weeds, and loofeu the foil for the free admiffion of air and 

 water. And the praftice feems to be generally well re- 

 ceived, and to have much effeft in promoting vegetation in 

 moft forts of vegetable . 



The management of the farmer and gardener fhould, of 

 courfe, aid and affift thefe views and intentions in every way 

 as much as poffible, in raifing and producing plants and 

 crops of different kinds ; as by the fuitable cultivation of 

 the ground, the proper application of manure or other fub- 

 ftances of that fort to it, the prefervation of the moifture of 

 it by different modes of cropping, and by every other prac- 

 ticable method in their power ; as by fuch means the perfeft 

 vegetation and growth of them may be the beft promoted 

 and affifted. See Fallowing Land, Pulverization, 

 Seed, &c. 



It may be obferved, that the fubftances or matters in land 

 which have hitherto been found injurious to vegetation, are 

 chiefly thofe of the metallic, fulphureous, aluminous, and 

 aftringent kinds. It has been noticed, that where mines of 

 iron, lead, or copper, are near the furface, no plants will 

 grow to perfeftion, as is well afcertained to be the cafe in 

 ^ R. 2 different 



