GEOGRAPHY OF CENTRAL FLORIDA 77

here described. But all of these points and many more are. covered, and some not only with reference to present conditions but also historically, i.e., the changes that have taken place in se.veral decades are outlined.

 PLAN OF DESCRIPTION AND SOURCES OF INFORMATION
 The description of each region follows as nearly as possible the outline given under General Features in the table of contents, but that of the smaller regions is necessarily less complete, on account. of the lack of census statistics for areas smaller than counties.
 The information about geology and underground waters is taken mostly from previous reports of this Survey, and that about soil texture from government soil surveys, which as yet however cover less than one-fourth of the area under consideration. The principal soil series and texture classes in each region sufficiently covered by soil surveys have been determined by picking them out from the maps, 'but it is hardly worth while to calculate their percentages until the work is more complete. Some of the chemical analyses of soils are taken from 19th century publications, and some were made for the Survey in 1915, from samples collected by the writer, by L. Heiniburger, one of the assistant state chemists at that time.
 The climatic factors discussed are only a few of the simpler ones, some taken direct and some computed, from publications of the U. S. Weather Bureau, chiefly Bulletins Q and W.
 The descriptions of vegetation are almost wholly from the writer's own observations, on about 100 different days, mostly in, the months of February, March, April and July, and in the years 1908-1910, 1914, 19Y5 and 1920. The importance of vegetation as an indicator of soil conditions is probably more generally recognized in Florida than in any other part o'f the United States; but in order to make satisfactory correlations between vegetation and soils it is necessary not merely to pick out certain species of plants supposed to be characteristic of certain soils, but to study the, vegetation quantitatively, as the census does population and' agriculture. The approximate relative abundance of the different species has been determined by consolidating or digesting the field notes taken in every county and region, on practically every mile of travel, whether by train, boat, automobile or on foot.