32 GENERAL HISTORICAL SUMMARY. 



concept of the formation is revised in the light of increased knowledge. Much 

 of the work also appeals to the exact ecologist because of the use of instrumental 

 and quadrat methods. Tansley's views upon the units of vegetation are dis- 

 cussed in Chapter VII, and the accounts of the different regions in the various 

 chapters are abstracted in Chapter XI. 



MacDmigal, 1914. — The work of MacDougal and his associates upon the 

 Salton Sea is outstanding in several respects. It is unique in dealing with 

 xerotropic succession from a wet saline habitat to a climax of desert scrub. 

 StUl more remarkable has been the opportunity offered by the flooding of the 

 Salton Basin and the gradual recession of the lake year by year, thus affording 

 a complete record of the stages of development in the series of zones from the 

 newest strand of 1913 to the oldest of 1907. It is even more significant, how- 

 ever, that the monograph is the result of the cooperation of ten specialists 

 in the various fields represented in this complex problem. This foreshadows 

 the future practice of ecology, when the study of vegetation has become 

 so largely quantitative that the investigation of the habitat in its climatic, 

 edaphic, and physiographic relations must be turned over to the experts in 

 these fields. The comprehensive nature of the research is indicated by the 

 following outline: geologic history, geographical features, sketch of the geology 

 and soils, chemical composition of the water, variations in composition and 

 concentration of water, behavior of micro-organisms, action of Salton Sea 

 water on vegetable tissues, tufa deposits, plant ecology and floristics, move- 

 ments of vegetation due to submersion and desiccation of land areas. A brief 

 account of the latter is given in Chapter X. 



