BOTANY. 



639 



parts must be distinguished from the accidental, and 

 that a scientific classification must be founded on the 

 former alone. Now it was obvious that the produc- 

 tion of fruit and seed is the ultimate object of 



r egetation, and, accordingly, in the first attempts at 

 lassification, the relations and component parts of the 

 eed and of the fruit were made the foundation of the 

 arrangement. This arrangement was confirmed by 



tion of oxygen to its other component parts gives the 

 various gradations and shades. Saturation with oxygen 

 gives the yellow and white colour. But if a plant saturated 

 with oxygen is exposed to the rays of the sun, the substance 

 of the light unites with the oxygen, the latter escapes, and 

 the plant reassumes its green colour. For the rest, the 

 colour seems to have its seat in the cellular substance; the 

 epidermis, however, is without colour. 



The chemical analysis of plants shows that all vegetable 

 matter consists chiefly of hydrogen, carbon, and oxygen. 

 Their different proportions produce the variety of vegetable 

 substances. Of these substances chemistry has distin- 

 guished gum, fecula or starch, sugar, gluten, albumen, 

 gelatin, caoutchouc or Indian rubber, wax, Ju.ed oil, vola- 

 tile oil, camp/tor, resin, gum-resin, balsam, extract, tannin, 

 acids, aroma, the bitter, the acrid, and the narcotic prin- 

 ciples, and ligneous Jibre. Several of these substances are 

 capable of transformation into each other. 1'hus the taste- 

 less mucilage passes into sugar or acid. These changes 

 are produced by heat, moisture, air, and the alkalies, which 

 change more or less the proportion of the original constitu- 

 ents. The formation, therefore, of the various substances in 

 vegetables is the consequence of truly chemical operations, 

 which may be traced from the germ to the ripe fruit. To 

 determine how the original constituents are absorbed by 

 light and heat, and united to each other by the vegetable 

 organization in such a manner that they produce the vari. 

 ous substances of which plants are composed, and which 

 again, in their last analysis, are resolved into those original 

 constituents this is the problem of vegetation. The way 

 in which plants grow, i. e. in which the nutritious parts 

 pass into the plants, is thus stated : Water and carbon re- 

 solve themselves into their constituent parts, enter into 

 new unions, and thus form the solid portions of plants. 

 Hydrogen separates from the oxygen in order to unite with 

 carbon, and thus oils, resin, and the like, are formed. At 

 the same time, oxygen is formed from the water and car- 

 bonic acid, and passes off, in union with caloric, as oxygen 

 gas. By means of these substances, the increase of the 

 vegetable fibres, or the proper growth, is produced, though 

 we are not able to see clearly the way in which it is ef- 

 fected. 



As to the fructification of plants, the same general theories 

 exist as in regard to the fructification of animals ; i. e. the 

 theory of evolution, which considers the germ of all crea- 

 tures as already existing, and only waiting for the process 

 which is to call them into life, and the more philosophical 

 theory of actual generation by a wonderful co-operation in 

 the two sexes. This process in plants takes place in the 

 following way, very similar to that in the -case of animals : 

 Plants have male and female organs of generation, which 

 may be observed by the naked eye; yet these parts aie 

 generally not permanent, as in the case of animals, but 

 change after fructification has taken place. The pollen or 

 farina is prepared and preserved in certain vessels destined 

 for this purpose, called anthers. Its finest part penetrates 

 through the stigma, an opening in the female part, through 

 the pistil to the ovary, and fructifies the germs or ovules 

 lying there. With most plants both sexes are united in one 

 flower ; with a few they are separated. The former are 

 called perfect flowers, the latter male or female. The two 

 latter either stand on one stem or belong to different plants. 

 With the (so called) perfect flowers fructification is effected 

 most easily ; and also, where the same stem has male and 

 female blossoms, no particular difficulty exists ; but where 

 the two sexes are entirely separated, fructification takes 

 place only when the two plants of different sexes stand 

 near enough for the pollen of the male plant to be carried 

 to the female by the wind or by insects. If this or an 

 artificial fructification does not take place, the germ eithei 

 falls off, or it forms a fruit, which, however, is incapable nl 

 germinating. Wonderful, indeed, are the means by which 

 nature effects the fructification of these plants ! Within 

 the flower of the plants are generally glands, which exude 

 a honey, by which insects are attracted ; but, in order to 

 I obtain this, they must powder themselves in the male 

 flowers with the pollen. Visiting afterwards a female 

 flower with the same view, they must deposit the pollen on 

 the pistil. In some other plants, where the male and fe 

 male parts in perfect flowers are placed so as not to be able 

 to reach each other, little flies are attracted by the honey 

 but immediately upon their entrance the flower closes, anc 

 thus the insects, who crawl in all directions to find a wa; 

 'f escape, are forced to fructify it. Grasses are general]; 

 fructified by the wind. Linna-.us founded bis system on 

 the generating organs of plants. (For an illustration o 

 this system, and a list of the genera and species indigenous 

 to Britain, with their situation, duration, and time of flower 

 ing, tee the annexed Chart, drawn up by Dr Rattray, sur 

 geon and lecturer on botany, Glasgow.) 



This sexual system (so called) has been opposed by 

 Schelver (Kritik der Lehre von den Gesclilechtern dir 

 3 flanzen (Heidelb. 1812), and Fortsetzung tier Kritik 

 Carlsruhe, 1814), and particularly Henschel, Ueber die 

 Sexualitat der Pjlanzen (Bresl., 1820), whose views have 

 ittracted much attention. They start from the principle 

 hat the animal has the advantage of the plant in indivi- 

 duality, both in the general structure and in that of the 

 various parts, and that the individuality which is the most 

 >romineut, is the animal generation ; on the other hand, 

 :hat with plants the similarity in the general structure, as 

 well as in that of the single parts, is incompatible with di- 

 versity of sex, and that therefore all proofs alleged in sup^ 

 port of the latter must undergo a re-examination. Hen. 

 schel undertook this ; but Treviranus, in his Die Lehre vom 

 Geschlechte der Pjlanzen (Brem., 1822), has contradicted 

 uost of his statements. Yet the famous K. Sprengel ad- 

 icres fully to Henschel's views. To this artifical system is 

 opposed the natural, which is founded on the presence or 

 absence of the chief organs, because plants differ from each 

 other chiefly in this way. Oken followed this system in 

 his Natural History for Schools (Leipsic, 1821). And such 

 a one only can give an insight into the great and beauti- 

 ful order of this vast kingdom of nature. See Decandolle's 

 Organographie Vigetale (2 vols., 60 engrav.). 



As a convenient manual, we would refer the reader to 

 Nuttall's Introduction to Systematic and Physiological Bo 

 tony, 2d edit, Cambridge (Massachus.), 1830. Respecting ve- 

 getable geography, see Schouw's Dtss. de Sedibus Planta- 

 rum originariis (1816) ; his Grundxuge einer Allg. Pjian- 

 geographie (Copenhagen, 1822; translated from the Danish 

 into German, Berlin, 1823); Atlas of Veget. Geography 

 (Berlin, 1824); Alexander von Humboldt's works; parti, 

 cularly the Introduction to Bonpland's work, Nova Genera 

 et Species Plantarum,by Kuni.li. 



Anatomy of Plants. A more accurate knowledge of the 

 organization of plants has been obtained chiefly by the 

 zealous and patient investigations of German and French 

 naturalists, as Sprengel, Link, Treviranus, Mirbel, Richard, 

 and many others. A short view of the organization of 

 plants must suffice for our purpose. 



I. General structure of Plants. The primitive form, 

 which appears in the earliest stage even of the lowest 

 plant, is the globule, which we may observe even in the 

 nourishing juice, which exudes from the inner bark (liber) 

 of trees. These globules, becoming connected, form a tex- 

 ture of cellules, which is universally diffused through the 

 vegetable world. The sides of these cells are entire, with- 

 out any apertures, so that one cell has no communication 

 with the others ; but the juices contained in them perspire 

 organically in the same way as those in the animal body. 

 In those cases in which the globules do not touch each 

 other on all sides, they leave interstices, which serve as 

 passages for the juices, particularly in trees with acicular 

 leaves. Yet these passages are very often wanting in the 

 cellular texture, because the little globules which form the 

 latter are attracted so uniformly, that regular spaces are 

 produced, the sides of which are perfect squares, penta. 

 gons, or hexagons. The cellular texture serves for the pre- 

 servation and preparation of the juices. Hence it is gen- 

 erally filled with mucilaginous, saccharine, oily, or resin- 

 ous substances. The cellular texture, in the more perfect 

 plants, has a remarkable connexion with the air. From 

 the ferns upward, it becomes more regular towards the sur. 

 face of the plant, and full of spaces, which ant filled with 

 air, received through apertures of a peculiar organization. 

 These apertures are found mostly where a green surface 

 covers the plant, most frequently, however, on the lower 

 surface of the leaves. They are more or less oval, gener. 

 ally surrounded by a glandulous ring, and have, some- 

 times, below them, small folds, which keep them open. 

 They may be considered as destined te inhale and exhale, 

 but merely gases, not watery liquids. The sacond ori- 

 ginal formation is the rectilinear, fibrous, or. more proper- 

 ly, tubular structure. Powerful magnifiers show that the 

 fibres are real tubes filled with juice, not continuous, but 

 here and there terminating in a point, e. g. in the liber 

 of trees, also in the alburnum and in the (so called) nerves 

 and ribs of leaves. Their first beginnings appear already 

 in the mucilaginous nourishing juice, where they have the 

 form of needles, and crystallize as it were in bundles 

 These tubes have the softest skin and the smallest diame- 

 ter among all the original formations ; yet they are ex- 

 tremely extensible and tough. They form what is spun as 

 flax, and what is obtained for useful purposes from hemp, 

 from the paper-mulberry, &c. Their chief purpose seen 

 to be the conducting of the ascending juices. The third 

 original formation is called tliespiralform, because it con 

 sists primitively of fibres spirally wound, which form th* 

 sidsa of cylindrical canals. This formation appears, from 



