SUCCESSION, AN ECOLOGICAL CONCEPT.

The term "succession" seems to have first gained currency and definition as a result of its use in the writings of the plant ecologists. It has not the same wide application in animal ecology, and where it has been used elsewhere, as it has by sociological writers, it seems to be a useful word but without as yet any very precise connotation. It has been used in describing the intra-mural movements and shillings of population incident to the growth of the city and of its various "natural areas." It has been observed that immigrant people ordinarily settle first in or near the centers of cities, in the so-called areas of transition. From there they are likely to move by stages from an area of first to areas of second and third settlement, generally in the direction of the periphery of the city and eventually into the suburban area-in any case, from a less to a more stable section of the metropolitan region. Although the term succession, as originally employed by sociologists, would seem to be more appropriately applied to movements of population and to such incidental social and cultural changes as these movements involve, there seems to be no sound reason why the same term should not be used to describe any orderly and irreversible series of events, provided they are to such an extent correlated with other less obvious and more fundamental social changes that they may be used as indices of these changes.