ECOLOGY. A phase of plant physiology which has recently come into prominence as an inde pendent subject is Ecology or (Ecology (q.v.), which deals with the mutual relations between plants and their environment. Certain phases of ecology. such as pollination, seed-dispersal, protection, symbiosis, have long been studied, and have been called 'plant biology'; but the subject as a whole is of very recent organization. Ecol egy as at present organized was first presented by Professor Warming. of Copenhagen. in IS95, and its fullest recent statement is that of Pro fessor Schimper, in 1S9S. The subject is yet in a very formative state. and its formulated state ments must be regarded as largely tentative. Three rather distinct lines of ecological investi gation have been developed. One deals with the reactions of plants, tissues, and organs to their environment, and may be called physiologic ecology. A second line has to do with the origin, development, and life relations of the plant com munities known as plant societies. and may be called physiographie ecology. The third line is a study of the great forest. grass, desert and other formations of the globe in relation to climate, and may be called geographic ecology.
Various special subjects connected with plants are also organized into distinct fields of work. Palrobotany (q.v.) is a study of fossil plants, a subject which has been developing with remark able rapidity. Barteriology is the science which treats of that very peculiar group of plants known as bacteria. whose relationships to the interests of man are often of great importance. and whose life-processes are so peculiar that they demand special manipulation. Pathology is that division of the subject which deals with plant diseases, chiefly those inflicted by other plants. It is this subject which has attracted a great deal of attention in connection with the work of agricultural experiment stations. Eco nomic botany. closely allied to agriculture and horticulture, is a growing subject, which deals with plants from the standpoint of their useful ness to man. Forestry is a special division of economic botany which studies the proper han dling of forests.
The literature of botany is too extensive to cite in any complete way, so that below are given only sonic of the more important works of a gen eral nature. Under the articles ANATOMY OF