the elder Pliny (23-79 A. D.), who writes of the garden Antonius Castor, at Rome, in which were grown a large number of medicinal plants. This step, however, may have been taken much earlier by the Greeks, Chinese, or Mexicans. Later the Benedictine monks of northern Italy paid great attention to the growing of remedial herbs, and devoted an important proportion of the monastery gardens to this purpose. This practice was also carried beyond the Alps, and in 1020 a garden was in existence at the monastery of St. Gall, in Switzerland, not far from Lake Constance, which contained 16 plots occupied by medicinal plants. A garden of this character was founded 1309 at Salerno, and another at Venice 1330.

some

The 16th and 17th centuries witnessed the foundation of many gardens in England, France, Germany, Holland, and Sweden, of which have had a continuous existence to this day. The garden of Bologna was founded 1568; Leyden, 1577; Leipsic, 1579; Montpellier, 1596; Paris, 1597. The last-named was organized for the determination of "what variations were possible in the style of bouquets worn at the royal courts." Then followed the establishment of the gardens at Giessen, 1605; Strasburg, 1620; Jena, 1629; Oxford, 1632; Upsala, 1667; Chelsea, 1680.

The number of these institutions at the present time is nearly 300, only a few of which, however, are devoted to the more important purposes named above. Many botanical gardens are merely municipal parks in which some attempt is made to exhibit special groups of plants, and are devoted chiefly to floriculture. Others are almost entirely experiment stations for the exhibition and testing of economic species, while still others find their chief usefulness as an aid in teaching botany in schools and

colleges.

D. T. MACDOUGAL,
Director of Laboratories,

New York Botanical Garden.

Botanical Geography. See DISTRIBUTION OF PLANTS.

Botany is that branch of biology, or the science of living organisms, which deals with plants, and is thus distinguished from zoology, which deals with animals. An individual plant, considered as a living or once living organism, may be studied in two ways-with reference to its structure or with reference to its functions. These represent the two great subdivisions of pure botanical science- anatomy and physiology respectively. All other phases of botanical science are special developments of one of these two, either alone or in combination with the other, or in relation additionally to some other branch of knowledge. Anatomy and physiology are thus the primary elements, as it were, of botany, which in varying combinations with each other and with the elements of other sciences constitute the branches of botanical science actually in existence, such as taxonomy, ecology, cytology, and pathology. The term plant anatomy is restricted frequently in actual use to gross anatomy and is often called structural botany. In this sense is covered about as much of the whole of anatomy as can be studied by the unaided eye or with a lens. Minute anatomy, or histology, covers the minute structure of plants,

the principal instrument in its study being the compound microscope. A study of the relationships of plants on the basis of anatomical resemblances constitutes comparative anatomy, or morphology. The classification of plants, known as taxonomy or systematic botany, is in the main a specialized branch of morphology, for the principal means by which plants may be grouped so as to indicate their genetic relationship is a comparison of their structural differences and resemblances. In its actual study plant physiology is closely associated with plant histology because most of the functions of the plant are intimately connected with the structure of plant cells, and the physiologist must of necessity understand these structures. A special branch of botanical research which has to do with the complex structure and activities of the plant cell is known as plant cytology. The study of the diseases of plants, whether they are due to fungi or other plant organisms, or are purely physiological, is plant pathology, sometimes called vegetable pathology.

History. Among the ancients, Aristotle the Greek philosopher (384 to 322 B.C.), Theophrastus his pupil (about 372 to 287 B.C.), the Roman naturalist Pliny the Elder (23 to 79 A.D.), and the Greek physician Dioscorides (of the 1st or 2d century A.D.) left botanical records of historical interest, but botany as a modern science has developed in the last four centuries, dating from the Reformation. The writing, particularly by the Germans, of herbals, or treatises on economic and medicinal plants, and the founding of botanical gardens, occupied most of the 16th century, but in the year 1583 Cesalpino, an Italian physician, published the first formal and comprehensive classification of plants. This, though artificial, formed the basis of all generally recognized classification to and including the time of Linnæus in the latter part of the 18th century. The 17th century was chiefly notable for advances not in the classification of plants, but in their structure and vital processes. Malpighi, an Italian, and Grew, an their researches on the gross anatomy and the Englishman, almost simultaneously published cellular structure of plants, the first of which were presented in 1671. To the work of these men in plant anatomy little of importance was added in more than a hundred years. The other important discovery of the century was the demonstration by Camerarius in 1691, through direct experiment, of the sexuality of plants. The 18th century was marked especially by advances in classification. In the year 1700 Tournefort published his 'Institutiones,' in which for the first time genera were systematically named and described. During this century Linnæus, the great botanical compiler and systematizer, brought out his successive works, culminating in the 'Species Plantarum, in 1753. It was later in the same century, too, that botanical exploration came to be recognized as an important department of the voyages of geographic and scientific discovery in which the nations of Europe became engaged. In 1789 A. L. de Jussieu published his Genera Plantarum,' in which was first systematically formulated a comprehensive classification of plants according to their natural relationship, as opposed to the artificial systems followed by Cesalpino and Linnæus. In the last two decades of this century were laid the foundations of our present know

ledge of the important part played by the air in the nutrition of plants, a proper conception of which was possible only in the light of the new developments which took place at that time in chemistry. The 19th century witnessed enormous strides in plant anatomy and plant physiology, the latter largely contributed to by workers in chemistry and physics, and the former rendered possible by improvements of the compound microscope and accessory instruments, especially those which came into general use about 1840. From this movement has been derived most of our knowledge of the life history and relationship of the lower groups of plants, the fungi, algæ, and lichens, and the assignment of the pines and their relatives to their true position next above the ferns. The whole realm of botanical research was profoundly affected by the work of Darwin, beginning with the publication of his 'Descent of Man, in 1858, which gave a new point of view for all subsequent work. In systematic botany the principle of the development of species from a common ancestor was substituted for the old view of the constancy of species. The remarkable adaptations for cross fertilization in the coloration, odor, and structure of flowers was given its true and significant explanation as a means for originating and perpetuating species. Darwin's work gave a new philosophical basis for the interpretation of observed phenomena and facts.

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Progress in the United States.-At the beginning of the 19th century the advancement of botany in North America was largely in the hands of physicians, through their requirement of a knowledge of plants as materia medica. Professors of botany were unknown. Linnæus and other great botanists in Europe had had American correspondents, and geographic expeditions accompanied by European botanical collectors had touched the margins of the continent. Some botanical exploration, chiefly by European visitors, had been effected east of the Alleghany Mountains. The centre of botanical activity was at Philadelphia, among the members of the American Philosophical Society. With Lewis and Clark's expedition across the continent to the mouth of the Columbia, in 1803-6, began a series of American explorations of the great interior, directed first to the Louisiana Purchase, then to Oregon, and finally to California. These were supplemented on the north by the British expeditions of Sir John Franklin and others in quest of a Northwest Passage. In the fifties began the Pacific Railroad surveys and these were followed by the geological surveys. All these contributed materials for the discovery, description, and orderly arrangement of the North American flora, the collections going largely into the hands of Thomas Nuttall at Harvard University, John Torrey at Columbia, Asa Gray, who was Nuttall's successor, and George Engelmann, a physician of St. Louis. Meanwhile appeared a new factor which was destined to play an important part in the development of botanical science in America, the establishment of agricultural colleges in the late sixties. These institutions created a demand for a class of botanists who did not exist in the United States or anywhere else, botanists who had brought a critical scientific training to bear on the hard problems of agriculture. For the succeeding two decades the universities of the country, including some of the agricultural colleges them

selves, were busily engaged in educating the required men, a movement which resulted in the preparation of many who were competent not only to act as teachers of botany in the agricultural colleges but, a still more important matter, to act as investigators in agricultural experiment stations, one of which was established in each of the States and Territories in the late eighties. The branch of botany which received its greatest impulse was pathology, the science of the diseases of plants. Plant pathology has already been carried to a point of high scientific development and practical application attained in no other country. Systematic, or, as it is now more commonly known, taxonomic, botany has made rapid strides forward in the past two decades, largely through the application of methods developed and perfected by American ornithologists. These methods differ from others chiefly in a full consideration of the geographic relationships of plants and the examination of very large series of specimens. A new revision of the whole North American flora along these lines and accompanied by systematic botanical exploration is now under way. For the future two lines of inquiry are likely to be conspicuous in American botany, first, the principles of heredity in plants and the applied phase of the subject, plant breeding on a scientific basis; and second, the correlation of plant functions with plant structures, a work which will have far-reaching importance in broadening our understanding of the processes of nature. The geographic location of American botanical research has undergone a profound change as a result of the Spanish-American war. The area to which up to that time the energies of American botanists had been chiefly directed was the north temperate belt of one hemisphere, but they now must deal in addition with botanical problems in the tropics of both the New World and the Old World.

Classification. The plant kingdom is divisible into five great groups, the Myrophyta, or slime molds; the Thallophyta, including the bacteria, algæ, fungi, and lichens; the Bryophyta, including the liverworts and mosses; the Pteridophyta, including the ferns and their allies; and the Spermatophyta, or flowering plants. The first four of these are often jointly designated as the Cryptogame, or cryptogams, in contradistinction to the Phanerogama, an older name for the flowering plants.

The Myrophyta, or slime molds, known also as the Myxomycetes, Mycetozoa, and Myrothallophyta, are organisms which though usually treated as belonging to the vegetable rather than the animal kingdom, have no cellulose walls covering the cells of which they are composed; pass a part of their life as plasmodia, or masses of naked creeping protoplasm similar to the animals known as amoeba; and are reproduced without even the simplest method of sexual regeneration. Most of them resemble fungi in that they grow upon decayed animal or vegetable matter. The Thallophyta include a wide variety of plants, associated with each other by exclusion, on the one hand, from the animal-like Myrophyta, and, on the other, from the Bryophyta and higher plants. The plant body is commonly not differentiated into stem and leaf, and may even be unicellular; a cell wall is usually present; chlorophyll is often wanting; and frequently sexual reproduction does not ex