ECOLOGY. 6S3 ECONOMIC ASSOCIATION. speak of this third subdivision under the head of DisTRinrxiox of Pl.xts (q.v. ). Pliysiological ecology, whether anatomical or organojrraphie, is oonwrned chielly with the origin and nieanini; of the tissues and orpans of plants. In the interpretation of this field there are two prominent theories, which may be briefly outlined. The older and conunoner theori" is based on teleological assumptions, and may be called the theory of purpose or design. The theory of design lias also had two aspects: (l)That in which rigid special creations were postulated in order to account for the relations between structures and functions: (2) that in which natural selection, acting for many gen- erations, was supposed to be the cause of special- ized structures obviously adapted for certain ends. The newer and less common theorj- is based on dysteloological assumptions, and may be called the accident or gall theory. Plant structures are regarded as the result of various purely physical and chemical forces; if a struc- ture is of value, it is but a matter of accident. .Tust as a gall is regarded by every one as the result of forces set in operation by the insect's sting, so all organs and tissues are the inevita- ble result of mechanical agents. Possibly the correct standpoint is an intermediate one. Struc- tures cannot be built., nor functions carried on. contrary to chemical and physical laws; but within certain limits there is perhaps room for successful variation, and hence for natural selection and the gradual improvement of struc- tures in relation to plant functions. Some of the arguments for natural selection and the teleological view are found in the structure and mechanics of stomata, which are the opposite of what one would theoretically expect; the stor- age of water or reserve foods is a phenomenon hard to account for without natural selection. Experiments show that some plants are rigid and some plastic; rigid plants have commonly lived for ages in rigid habitats, as is particu- larly true of desert plants. Plastic plants, on the other hand, often live in variable habitats, the best examples of all plastic plants being the amphibious species. It would seem as if per- manence of habitat causes the development of rigid structures, as is well shown in the Be- gonia, which has remained xeroph.vtic in struc- ture through generations of mesophytic culture — i.e. culture in moist surroundings. And it would seem as if the marvelous plasticity of such plants as Ranunculus. Nasturtium. Polyg- onum. Proserpinaca, Sium, etc., is a result of long life in variable habitats. The desert plant shows the natural selection of adapted but rigid forms, while the amphibious plant shows the selection of the capacity to varj*. a far subtler type of selection. While these argu- inents favor the natural selection and teleolog- ical theories, current dysteleological views have certainly clarified the atmosphere. The extreme views of some teleologists. who sec a purpose in everything, must surely be discarded; but it re- mains for the future to strike a proper balance between the design and accident theories in rcologv'. For the present, therefore, the ecolo- gist should strive to ascertain the influence of external agents on plant form, and should also seek to discover the advantages possessed by certain forms in the performance of the plant functions, but should leave the determination of the exact relation between form and func- tion to future investigation. The subject-matter of anatomical ecologj' is not iiresented as such in this work. The purely morphological aspects are treated under Anat- omy OF Plants. Anatomical matter is also pre- senteil in connection with the topics Hyoro- piiYTK; Xkroi'iiyte; Leaf; Root: Symbiosis. Organograi)hic ecology will be treated in con- nection with the various organs of |)lants (see I.iCAi'; Ste.m: Root: Seed; Polli.nation ; also t oi.oit : Di'RATiox : Vegetative Proi-acation ) , and with various plant forms. (See Epiphytes: l.iA.NAs: Saprophytes: SYMniosis. ) The topics treated in physiographic ecology, and to some extent in phytogeography. involve organographic material. Pliysiographic ecology will be treated from the standpoint of topographic habitats (sec Beach Plants; Benthos; Dune Vegetation; Heath: Meadow: Plankton; Rock Plants; Rideral Plants), as well as from the stand- point of the water relations (see Hydrophyte, Mesophyte, Xerophyte) and chemical relations of the soil. (See Halophyte. ) The ecological aspects of geographic botany are presented under Distribution of Plants: Axpine Plant: Desert Vegetation; Forest; Grassland; Thicket. Bibliography'. Costantin. La nature tropi- cale (Paris, 1S99) ; Flahault, Essai (Tune carte botanique et forestiire de la France (Paris. 1897) : Goebel, Organography of Plants (Oxford, Eng., 1900) ; Haberlandt, Fhysiologische I'jlan- zenanatomie (Leipzig, 1896) ; Eine botanische Tropenreise (Leipzig, 1893) ; Lubbock. Buds a7id Stipules (London, 1899) ; Ludwig, Lehrbuch der Biologic der Pflansen (Stuttgart, 1895); Wies- ner. Biologic der Pflanzcn (2d ed., Vienna, 1901 i ; Kerner. Natural History of Plants, trans, by Oli- ver (London, 1895) : Coville, "Botany of the Death Valley Expedition," in United States De- partment of Agriculture (Washington, 1893) ; Gray, Scientific Papers (Boston, 1889) : Kearnay, Botanical Survey of the Dismal Stcamp Hcgion (Washington, 1901): Macilillan, iletuspermw of the }linnesota Valley (Minneapolis, 1892) : Mayr, Waldungen von yardamerika (Munich. 1890) ; ]Ierriam. Life Zones and Crop Zones of Ihe United States (Washington, 1898) ; Pound and Clements, Phytogeography of Xebraska (Lincoln. 1900). Consult also authorities re- ferred to under Botany ; Distribution of Plants. ECONOMIC ASSOCIATION, .merican (Lat. (ceonomicus, from Gk. oiKdyD/jjfidc, oikonomi- kas. relating to the management of a houseliolri. from o'lKovoyla, oikonomia, management of ii household, from oXkos, oilcos, house + w/tios, nomos, law). An organization formed in 1885 and composed mainly of persons interested in the study of political economy or the economic phases of political and social questions. In 1001 it had about 000 members, made up al)out equally of teachers of political economy and related sub- jects, and business men. journalists, lawyers, and politicians interested in the theories of political economy and their application. Its chief feature is its aimual meeting, which usually takes place in the last week in December, a convenient city being selected in the East and West in alternate years. The publications of the association con- sist of an annual report, giving the proceedings
