BOTANY. 



573 



and prevent its darting on the lips ; but the fly watch- 

 ing for a favourable opportunity, continues to repeat 

 the operation from time to time," till at length finding 

 this mode of defence insufficient, the enraued animal 

 endeavours to avoid it by galloping away to a distant 

 part of the field. If it still continue to follow and 

 tease him, his last resource is in (he water, where the 

 oestrus is never observed to follow him. At other 

 times, this oestrus gets between the fore-legs of the 

 horse whilst, he is grazing, and thus makes its attack 

 on the lower Hp ; the iitillation occasions the horse 

 to stamp violently with his fore-foot against the 

 ground, and often strike with his foot as though 

 aiming a blow at the fly. They also sometimes hide 

 themselves in the grass, and as the horse stoops to 

 graze they dart on the mouth or lips, and are always 

 observed to poise themselves during a few seconds in 

 the air, while the egg is preparing on the point of the 

 abdomen." 



The Gasterophihts nasalis of Linnaeus (CEstrns) is 

 described by Mr. Clark under the name of (Estrus 

 veterinus. 



BOTANY is that science which includes the 

 study and investigation of the vegetable kingdom. 

 To describe and enumerate plants, to give to them 

 their proper names, to mark their habits, physical 

 differences and qualities, to arrange them into divisions 

 by their organic structures, into tribes by their most 

 ostensible characters, into families by their affinities 

 and essential synonyms, and each individual of the 

 families by its specific distinctions, is the business of 

 the practical botanist. 



Systematic botany was first projected by Conrad 

 Gesner above tsvo centuries ago. In the course of 

 time the science was gradually improved, particularly 

 by Tournefort and his cotemporaries ; but it was 

 reserved for the celebrated Linnaeus to concentrate 

 and reduce all that had been written before his time 

 into his ingenious though artificial sexual system. 

 Before the appearance of this new system, that of 

 Tournefort was chiefly received and studied, and, 

 though imperfect in many particulars, it had many 

 excellencies, especially in preserving several of the 

 true natural orders entire. Linnaeus himself it seems 

 felt the propriety of such an arrangement of plants, 

 and had before his death made some progress in 

 sketching a natural classification, but did not live to 

 render it in any way complete. The idea, however, 

 was not lost, but was approved and strenuously 

 embraced by the indefatigable Jussieu, who, seeing 

 the defects of the sexual system and the superiority 

 of that of Tonrnefort, set about re-arranging the latter, 

 and has by dint of great labour and extensive botani- 

 cal knowledge, laid the foundation of a system which, 

 with subsequent corrections and amendments of other 

 botanists, comes as near to perfection perhaps as such 

 an attempt can possibly be; for nature, notwith- 

 standing she presents some very striking features of 

 similitude in vegetable forms and structure, yet in 

 general the diversity of external figure and conforma- 

 tion is so great and unlimited that many of Jussieu's 

 groups must necessarily be small, and the number of 

 the groups greatly increased in order to embrace 

 every plant, and yet not depart from the grand prin- 

 ciple on which the natural system is founded. 



In presenting to the reader a general view of this 

 interesting portion of natural history, it will be neces- 

 sary, before treating of systematic botany, to describe 



the physical members of plants, that is, those different 

 parts or organs which compose the vegetable frame, 

 their apparent uses or functions, the character of 

 their various membranes, their duration, decay, and 

 reproduction, together with the nature and motion of 

 the sap. In the prosecution of this detail, we shall 

 have occasion to notice every grade of vegetation 

 hitherto described, so that the reader may have as 

 comprehensive a view of the whole as can be exhibited 

 within the prescribed limits of a cyclopaedia. 



Before proceeding with a description of the various 

 members of a plant, it is in the first place necessary 

 to convey some idea of the membranes of which they 

 are composed. 



Vegetable membrane. This is one of the results of 

 Almighty creative power, which, by the concentration 

 or union of pre-created elements, called into form 

 every plant whose seed or power of extension is in 

 itself. This membrane is composed of innumerable 

 distinct vesicles, variously arranged with respect to 

 each other ; each having a thin pellucid elastic 

 integument, originally uninflated and inconceivably 

 minute, but capable of being distended to a limited 

 size, but in a definite order incident to the plant to 

 which they belong, and in any direction. Leaning 

 closely on each other, the cells are pressed into the 

 various figures of spheres, spheroids, elongated cubes 

 or ovals, forming the specific organic structure. There 

 are also intercellular spaces which serve for the con- 

 duction of fluids or depositories of the secretions of 

 the plant. Of this membrane every part of the vege- 

 table is formed ; it being capable of extension into 

 filaments and fibres, fig. 1 ; spread out into tissues, 



Fig. 1 . 



Fig. 2. 



fig. 2 ; depressed into horizontal layers, fig. 3 ; 

 Fig. 3. 



compressed into perpendicular partitions; or dis- 

 posed in regular columns. When it is uniform in 

 consistence and arrangement it is called cellular; 

 when varied by being disposed in tubes, fibrous 

 bundles, or other organic forms, it is said to be 

 vascular. 



In describing a plant it is usual to begin with the 

 root, but as a seed or some dissevered part of a plant 

 must exist before roots can be produced, it may be as 

 well to begin with the description of a seed, because 

 from it springs every other member which we shall 

 have occasion to notice in the sequel. 



Seed. Seeds are the oviparous offspring of plants. 

 They are discharged spontaneously from the parent 

 in a dormant state, except in some few instances 



