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VEGETABLE KINV.DOM. 



VEGETABLE KINGDOM. 



the various form* of Plants, u the term* Animal and Mineral King- 

 dom! are applied to Animal* and Mineral*. The distinction! which 

 are supponed to limit these three kingdoms are treated of in the article 

 AMMAI KINGDOM. We shall here speak of the uses, general features, 

 and distribution of Plant*. 



The Vegetable Kingdom performs important offices in the economy 

 of creation. It (tends between the mineral and animal kingdoms, 

 disposing and arranging the elements of the first in order to fit them 

 for the purposes of the last Each of the three kingdoms of nature 

 is composed of matter as iU basis ; but the animal kingdom directly 

 appropriates no portion of the elements of the inorganic world to its 

 use*, but derives them all from the vegetable kingdom. The researches 

 of chemist* show that the proximate principles of animal bodies are 

 identical with tboee of vegetables, and that consequently, as these 

 principles do not exist in the inorganic kingdom, they must hare been 

 formed in pliints. Thus we mnst regard the vegetable kingdom as one 

 vast chemical laboratory, in which the food of animals is being pre- 

 pared. Without vegetables animals would perish, and although some 

 animals lire on the fleah of others, yet that flesh is always originally 

 derived from the vegetable kingdom. The proximate principles of 

 plants are not numerous, and are composed of hydrogen, oxygen, 

 nitrogen, and carbon ; those containing nitrogen are directly appro- 

 priated by animals to the formation of their tissues, whilst those 

 containing no nitrogen are either consumed in generating animal heat 

 or deposited in the form of fat. When animal bodies cease to exist, 

 their tissue* become resolved into their primitive elements, a process 

 which is constantly going oa in animal bodies during life. These 

 elements, in the state of various compounds, are carried off into the 

 atmosphere when gaseous ; or assist in forming the soil on the surface 

 of the earth when solid. The principal compounds which are thus 

 generated are carbonic acid and ammonia : and if accumulation of 

 these gases took place to any extent in the atmosphere the conse- 

 quence* would be a cessation of vitality in both the animal and 

 vegetable kingdoms; but here again plant* perform an important 

 office, for these very compounds combined with water are the prin- 

 cipal sources of the elements which plant* elaborate into so many 

 secretions necessary to the existence of animals. There is thus a 

 relation established between the animal and vegetable kingdoms, of 

 which man has extensively availed himself in the application of 

 manures to the artificial production of food. In this relation too are 

 involved the laws of the production of plants for food in communities 

 with circumscribed districts, to the investigation of which compara- 

 tively little attention has been given. 



In addition to supplying food and purifying the atmosphere for 

 animals, the vegetable kingdom is made use of extensively by man. 

 The larger forms of plant* are used for the building of house* and 

 ihipc, the construction of furniture, and a thousand implements 

 necessary in the arts of life. The various secretions of plants, their 

 oils, resins, acid*, neutral and alkaline principles, all exert a powerful 

 agency on the human system, and are employed for the purpose of 

 controlling, changing, and interrupting tlie diseased actions to which 

 man U subject. Another large class of plants furnishes him with 

 luxuries, as tobacco, tea, coffee, spices, perfumes, and fruits of various 

 kind* ; and to these mutt be added fermented liquors, which are all 

 produced from the fermentation of the saccharine juices of plants. 

 A great part of the clothing of man is the produce of the vegetable 

 kingdom : cotton, flax, and hemp are of vegetable origin, and when 

 the fabrics which are made from them are worn, they are mostly 

 coloured with the secretions of the turmeric, indigo, orchil, catechu, 

 and others. 



Climate is also modified by the vegetable kingdom. The presence 

 of thick foret intercepts the ray* of the sun, and the earth has a 

 lower temperature in consequence. On the other baud, the heat of 

 the surface of the earth is changed by the difference of radiating 

 power between plant* and the soil on which they grow. The constant 

 nbftorption and exhalation also of a large body of plants will affect 

 tlie humidity of the atmosphere according to the circumstances in 

 which they may be placed. Another consequence of the existence of 

 plant* is the production of malaria during tlicir decay. There U 

 perhaps no fact better proved than that decaying vegetable matter is 

 the wurce of the most dreadful pestilences that affect human beings. 

 The direct agency l>y which this is effected is unknown ; it is called 

 malaria, and is alike produced by decaying plants in the swamps of 

 Afiicn, the jungles of India, the savannahs of America, and the ditches 

 of Europe. No part of the world where vegetables are produced is 

 free from iU iuflnrnce; and even in large cities, perhaps the only 

 place* susceptible of being made a refuge from its scourge, needless 

 accumulations of decomposing vegetable matter are allowed to become 

 the source of disease and death. 



Plants also give peculiar features to the surface of the earth, and by 

 their distribution the life of the animal kingdom u regulated. Although 

 each plant appears to have a special constitution, by which it* exist- 

 ence in particular part* of the earth ii determined, certain external 

 agent* exercise a controlling influence, and to these we shall now refer. 



Of the agent* that dttcrmine the distribution and character of 

 plants none have more influence than light. Wherever plant* have a 

 large supply of light, there will the vegetation be prolific, and all the 

 Mentions of plant* will abound. It is by this agent that the functions 



of absorption, exhalation, and the decomposition of carbonic acid and 

 other compounds ore effected by plants. It is, in fact, a powerful 

 stimulant of vegetation, and it acts as all stimulant* do on organic 

 bodies. If a plant is withdrawn from its influence, it becomes weak, 

 its tissues soften and are filled with water, and few or no secretions 

 are deposited ; on the contrary, if plants are supplied with continued 

 light, they become oventimulated, they decompose carbonic acid 

 rapidly, and become stunted in their growth on account of the rapid 

 development of solid secretions. The influence of this agent is seen 

 remarkably in the vegetation of the surface of the earth. In the 

 tropics the direct rays of the sun are felt by plants, and under their 

 influence a prolific and gigantic vegetation is developed, but this arise* 

 from the alternate withdrawal and presence of this agent during every 

 24 hours, and as this is constantly the case, vegetation remains the 

 same throughout the year. On the other hand, at the poles, only the 

 oblique rays of light are felt, and consequently its influence is com- 

 paratively feeble. The gradations of vegetation may be seen, under 

 the influence of this agent, in passing from the tropics to the pole*. 

 From the magnificent baobabs, banyans, and palms of the tropics, we 

 pass through the regions of oaks, elms, and firs, of temperate climates, 

 till in polar regions the only representatives of trees are a few bramble*, 

 and tho majority of plants are mosses and lichens. 



Another agent is heat By some this has been supposed to have 

 more influence than light on the distribution of plants, but it is 

 difficult in nature to separate its influence from that of light, since it 

 is derived from the same source at the same time. However experi- 

 ments on a large scale are constantly going on in European hothouses, 

 in which it is proved, that although tropical plants be supplied with 

 their natural temperature, nothing will make up for the want of light, 

 and many of them seldom produce their flowers and less seldom their 

 fruit, and after a languishing existence soon die. The influence of 

 heat on vegetation U seen in those climates where there is a great dif- 

 ference of temperature between summer and winter. The plants of 

 such districts that live throughout the winter are so constructed that 

 they are enabled to bear the cold of winter. They have frequently 

 thick barks, in which are deposited resinous secretions, and are thus 

 enabled to withstand the decrease of temperature. It is also found, 

 for this reason, that those plants which thrive in hot summers are 

 best adapted to withstand the cold of winter, on account of the greater 

 amount of solid secretions deposited in their bark, and many plants 

 which flourish in districts where there are hot summers and severe 

 winters will perish in climates where the extremes of bent and cold 

 are not so great. Thus many plants will grow around Paris, where 

 the extremes of heat and cold ore great, which will not grow around 

 London, where these extremes are less; and the same holds good 

 with regard to London and Edinburgh, and the floras of the south uf 

 England and the north of Scotland afford abundant evidence of the 

 truth of this position. 



Water, as on agent affecting vegetation, must be regarded in two 

 points of view : first, as existing in the atmosphere as vapour, modify- 

 ing temperature, and controlling the function of exhalation and 

 absorption in plants ; and, secondly, as existing on the surface of the 

 earth in the form of oceans, rivers, lakes, swamps, &c. The compo- 

 sition of the waters of these lust also, or rather the substances which 

 may bo dissolved or suspended in the water, produce considerable 

 effect upon vegetation. Many OrMdactai are only found in the humid 

 forests of the tropics. The vegetation of sea* and lakes varies with 

 the circumstances of the ingredients they contain in solution, and with 

 the comparatively restless or quiet condition of their waters. Swamps 

 produced by overflowings of the sea produce different plants from those 

 produced by accumulations of fresh waters from mountain sides. 



The diameters of the soil influence the vegetation of particular 

 districts. The previous agents exert an influence on vegetation whidi 

 i* most evident in the characters of the great mas* of plants of a 

 district ; but the soil produce* effects on almost every individual 

 plant The influence of soil arises from its mechanical character and 

 chemical composition. The mechanical character of most importance 

 i* its amount of disintegration. Some plants, as lichens, grow on tho 

 surface of rocks and large stones, and are not found in districts where 

 these are not present Some require a loose soil for the free passage 

 of their roots, and are only found growing in sands. Others again 

 will only exist in tenacious soils, and are found growing in claya. The 

 mechanical character of soils also greatly influences their relation to 

 the absorption and radiation of heat, and thui affects the temperature 

 of the soil 



The last influence to which we shall refer is the atmosphere. 

 Chemically it remains in its great constituents, oxygen and nitrogen, 

 constantly the same. But the quantity of the vapour of water which 

 it contains, and whatever raits that vapour may bo capable of con- 

 taining, cause it to vary much. The influence of these a?< i 

 the air however is not different from the same in the soil Tho 

 agitation of the air by constant wind* has often an important influence 

 on vegetation, and the barren hills and coasts of many countries are 

 owing to the impossibility of plants withstanding the influence of 

 strong winds. The density of the atmosphere is a point of import- 

 ance, and seems to disturb the relation between elevation and latitude. 



Several methods have been proposed by De Candolle and other 

 botanists for giving an idea of the distribution of vegetation over the 



