308 Annals of the Carnegie Museum. 



physiographic ecology of Chicago and vicinity. ^^ More recently 

 Clements has brought forward the idea that the ecological conditions 

 of the habitat can be instrumentally determined, and the formation 

 thus be designated as a definite structure.^' 



In his studies on Presque Isle the writer did not use instrumental 

 methods, neither the time nor the instruments for such work being 

 available. However, a season's residence on Presque Isle, following 

 out the instrumental methods as proposed by Clements, would form 

 the basis for a very valuable ecological contribution and it is hoped 

 that sometime such a study may be carried on at this place. Never- 

 theless the ecological conditions obtaining in the various habitats on 

 Presque Isle are so profoundly different, and these differences are so 

 plainly apparent, the successions are so rapid, so condensed, and, at 

 the same time, present so complete a series of stages, practically free 

 from the destructive effects of civilization, that there seemed abundant 

 reasons for a survey such as has been made. Such a survey, although 

 perhaps more properly termed a reconnaissance, must, nevertheless, 

 precede a more exact and detailed investigation, or, in the absence of 

 further work in the near future, will stand as a valuable record of the 

 present larger ecological structure. 



Taking up now the structure of the formation, there are to be dis- 

 tinguished in the formation, at all times, one or more dominant species 

 termed the fades. Associated with each facies are usually other 

 prominent species, the whole group constituting a consocies. Areas, 

 the appearance of which changes from one season to another, being 

 dominated by principal species other than the facies, are termed 

 societies, and the different seasonal periods aspects. The aggregation 

 of parent and offspring constitutes a group termed \h& family, and the 

 grouping of families forms a community. 



No attempt has been made in the present contribution to use a 

 Latin nomenclature for ecological structures. The successions have 

 been designated by their important formations, and the formations 

 and their minor structures by their facies or principal species 

 respectively. 



There has been, and still is, considerable confusion in ecological 

 nomenclature, different authors having adopted the same term for 



^^Cowles, H. C. " The Physiographic Ecology of Chicago and Vicinity." Bot. 

 Gaz., 31 : 73-108, 145-182, February and March, 1901. 

 2» Clements, Y. E. /. c. 



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