BOTANY is that branch of science which comprehends all that relates to the Vegetable Kingdom. The term Botany is derived from the Greek, in which Bombe; signifies any kind of grass or herb, and $0-raysei time art which teaches the nature of plants and herbs. Time structure of plants, their mode of growth, their habits of life, their mutual relations, their uses to man or the danger that results from their employment, the station they occupy in the scale of the creation, and many other similar considerations, form each an exteneive field of inquiry which botany combines into one connected whole.
Although the limits of the science of Botany can be easily defined to be the structure and functions of plants, it is not so easy to define the nature of a plant. It is true that with regard to the great mass of organic forms which belong to the vegetable kingdom there is no difficulty in at oneo assigning them their position, but there are a very large number of organised bodies that stand in such intimate relations with the animal kingdom as to create a perpetual difficulty with regard to their real nature. At the time when it was considered • sufficient distinction between plants and animals that the former wore fixed and the latter had the power of locomotion, large orders of beings which are now classed with plants were regarded as animals. To some of these it may be interesting to draw attention, as it is amongst them that the uaturalint is enabled to observe in its simplest forma the true nature of the functions of vegetable structure. It Was in the large order Algm [Ato.1:1, to which belong the various forms of ma-weeds, and the lowest orders of plants inhabiting fresh-water, that those functions were first observed that were supposed to be peculiar to animal& Amongst the Oscillaterim it was found that a number had a distinct power of self-movement, so that as far as these were concerned it became evident that locomotion would not distinguish plants from animals. Many of the early observers with the microscope had Mao seen that the spores or cells that represented seeds in the higher ',hada had the power of motion. In order to distinguish between these movements and those possessed by the ova of animals, it was supposed that the latter had cilia whilst the former had not Unger and Thuret however; in 1S43, both announced the fact that the of many .1 /fife possess vibratile cilia, not to be
distinguished from there, on animal bodies. This important discovery has been followed by a very rigid examination of the various organised bodies admitted by Ehrenberg, into the class of Animalcules, in his 'Infunionethierchen,' on account of their locomotion by means of cilia. The consequence has been that large numbers of the Infesorea of Ehrenberg aro now regarded as plants. 0I10 of the most remarkable of them is the Faroe otobaior, or Globe Animalcule, which, although endowed with cilia and possessing the moat active powers of motion, has through the recent researches of Professor Williamson and Mr. Busk been shown to be an undoubted plant. Not only does the history of its development and its mode of reproduction bear out this conclusion, but also the presence of starch, detected by Mr. Busk during the growth of the youug retro% (' Microscopical Transactions,' vol. i. New Series). The placing this form in the vegetable kingdom is important., as a large number of the forms placed by Ehreuberg near Foirox must now be regarded also as plants. This serves to remove the anomaly which has sometimes been insisted on, that the lower animals perform the functions of the higher pleats, that is, take up carbonic acid and throw out oxygen. The fact is, these lower animals are plants. [Aelum. KINGDOM.] Ehrenberg also describes and figures the families of Diatonmeem and Darmidem in his Infusoria. They have the power of movement but are destitute of cilia. The Dermidem contain chlorophyle, are developed similar to the A tym, and the fact of their conjugating after the 'limner of the Zygnirmata amongst the Alga., first observed by Mr. Thwaites, has led naturalists to place them amongst ',bulbs. Mr. Rails, whose work on the 'British Desmidene' is one of the best on the subject, states that he has found starch universally present amongst them. The Dialomacrm are not so decidedly vegetable in their nature. Lindley in his Vegetable Kingdom,' however, admits Diotomacm, and regards Desmidem as a sub-kingdom. The pnaaence of a shell or frustule of silica, sometimes very complicated in its structure, has led Schleiden to reject the Diatomacem as Omits, whilst Kiitzing admits some and rejects others. Their general resemblance to Desnadrie lute given them their position in the vegetable kingdom.