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 existence of pollen tubes, and he was followed by A. T. Brongniart and R. Brown. The latter traced the tubes as far as the nucleus of the ovule. These important discoveries mark a new epoch in embryology, and may be said to be the foundation of the views now entertained, which were materially aided by the subsequent elucidation of the process of cytogenesis, or cell-development, by Schleiden, Schwann, Mohl and others. The whole subject of fertilization and development of the embryo has been more recently investigated with great assiduity and zeal, as regards both cryptogamous and phanerogamous plants, and details must be sought in the various special articles. The observations of Darwin as to the fertilization of orchids, Primula, Linum and Lythrum, and other plants, and the part which insects take in this function, gave an explanation of the observations of Christian Konrad Sprengel, made at the close of the 18th century, and opened up a new phase in the study of botany, which has been followed by Hermann Müller, Federico Delpino and others, and more recently by Paul Knuth.

One of the earliest workers at plant physiology was Stephen Hales. In his Statical Essays (1727) he gave an account of numerous experiments and observations which he had made on the nutrition of plants and the movement of sap in them. He showed that the gaseous constituents of the air contribute largely to the nourishment of plants, and that the leaves are the organs which elaborate the food; the importance of leaves in nutrition had been previously pointed out by Malpighi in a short account of nutrition which forms an appendix to his anatomical work. The birth of modern chemistry in the work of J. Priestley and Lavoisier, at the close of the 18th century, made possible the scientific study of plant-nutrition, though Jan Ingenhousz in 1779 discovered that plants incessantly give out carbonic acid gas, but that the green leaves and shoots only exhale oxygen in sunlight or clear daylight, thereby indicating the distinction between assimilation of carbonic acid gas (photosynthesis) and respiration. N. T. de Saussure (1767–1845) gave precision to the science of plant-nutrition by use of quantitative methods. The subjects of plant nutrition and respiration were further studied by R. J. H. Dutrochet towards the middle of the century, and Liebig’s application of chemistry to agriculture and physiology put beyond question the parts played by the atmosphere and the soil in the nutrition of plants.

The phenomena of movements of the organs of plants attracted the attention of John Ray (1693), who ascribed the movements of the leaf of Mimosa and others to alteration in temperature. Linnaeus also studied the periodical movements of flowers and leaves, and referred to the assumption of the night-position as the sleep-movement. Early in the 19th century Andrew Knight showed by experiment that the vertical growth of stems and roots is due to the influence of gravitation, and made other observations on the relation between the position assumed by plant organs and external directive forces, and later Dutrochet, H. von Mohl and others contributed to the advance of this phase of plant physiology. Darwin’s experiments in reference to the movements of climbing and twining plants, and of leaves in insectivorous plants, have opened up a wide field of inquiry as to the relation between plants and the various external factors, which has attracted numerous workers. By the work of Julius Sachs and his pupils plant physiology was established on a scientific basis, and became an important part of the study of plants, for the development of which reference may be made to the article : Physiology. The study of form and development has advanced under the name “morphology,” with the progress of which are associated the names of K. Goebel, E. Strasburger, A. de Bary and others, while more recently, as (q.v.), the intimate study of the cell and its contents has attracted considerable attention.

The department of geographical botany made rapid advance by means of the various scientific expeditions which have been sent to all quarters of the globe, as well as by individual effort (see : Distribution) since the time of A. von Humboldt. The question of the mode in which the floras of islands and of continents have been formed gave rise to important speculations by such eminent botanical travellers as Charles Darwin, Sir J. D. Hooker, A. R. Wallace and others. The connexion between climate and vegetation has also been studied. Quite recently under the name of “Ecology” or “Oecology” the study of plants in relation to each other and to their environment has become the subject of systematic investigation.

The subject of palaeontological botany (see ) has been advanced by the researches of both botanists and geologists. The nature of the climate at different epochs of the earth’s history has also been determined from the character of the flora. The works of A. T. Brongniart, H. R. Goeppert and W. P. Schimper advanced this department of science. Among others who contributed valuable papers on the subject may be noticed Oswald Heer (1809–1883), who made observations on the Miocene flora, especially in Arctic regions; Gaston de Saporta (1823–1895), who examined the Tertiary flora; Sir J. W. Dawson and Leo Lesquereux, and others who reported on the Canadian and American fossil plants. In Great Britain also W. C. Williamson, by his study of the structure of the plants of the coal-measures, opened up a new line of research which has been followed by Bertrand Renault, D. H. Scott, A. C. Seward and others, and has led to important discoveries on the nature of extinct groups of plants and also on the phylogeny of existing groups.

Botany may be divided into the following departments:—

1. Structural, having reference to the form and structure of the various parts, including (a) Morphology, the study of the general form of the organs and their development—this will be treated in a series of articles dealing with the great subdivisions of plants (see, , , , , , and ) and the more important organs (see , , , , ); (b) Anatomy, the study of internal structure, including minute anatomy or histology (see &#8202;).

2. (q.v.), the intimate structure and behaviour of the cell and its contents—protoplasm, nucleus, &c.

3. Physiology, the study of the life-functions of the entire plant and its organs (see : Physiology).

4. Systematic, the arrangement and classification of plants (see : Classification).

5. Distribution or Geographical Botany, the consideration of the distribution of plants on the earth’s surface (see : Distribution).

6. Palaeontology, the study of the fossils found in the various strata of which the earth is composed (see ).

7. Ecology or Oecology, the study of plants in relation to each other and to their environment (see : Ecology).

Besides these departments which deal with Botany as a science, there are various applications of botany, such as forestry (see ), (q.v.),  (q.v.), and materia medica (for use in medicine; see the separate articles on each plant).

 BOTANY BAY, an inlet on the coast of Cumberland county, New South Wales, Australia, 5 m. south of the city of Sydney. On its shore is the township of Botany, forming a suburb of Sydney, with which it is connected by a tramway. It was first visited by Captain Cook in 1770, who landed at a spot marked by a monument, and took possession of the territory for the crown. The bay received its name from Joseph Banks, the botanist of the expedition, on account of the variety of its flora. When, on the revolt of the New England colonies, the convict establishments in America were no longer available (see and ), the attention of the British government, then under the leadership of Pitt, was turned to Botany Bay; and in 1787 Commodore Arthur Phillip was commissioned to form a penal settlement there. Finding, on his arrival, however, that the locality was ill suited for such a purpose, he removed northwards to the site of the present city of Sydney. The name of Botany Bay seems to have struck the popular fancy, and continued to be used in a general way for any convict establishment in Australia. The transportation of criminals to New South Wales was discontinued in 1840.