REVIEWS 479 



condition), leading to the main body of the text. The style is uniform 

 — a page of description facing one of drawings, with keys to the species. 

 Some bark illustrations are given. 



One additional feature in this publication is the section relating 

 to the common lumber woods. The subject of wood structure is 

 briefly taken up, followed by an artificial key to the species of wood. 



J. H. W. 



Plant Succession. An Analysis of the Development of Vegetation. 

 By F. E. Clements. Publication 242, Carnegie Institution of Wash- 

 ington. Washington, D. C. 1916. Pp. 512. 



To review a book of such size and importance as this volume, and 

 to bring out the special interest which the forester has in it, must be 

 left to competent hands and time. For the present, we consider it, 

 however, proper to give at least this book notice, in order to make our 

 readers cognizant of its existence. 



Briefly stated, it is a critical analysis of the facts and principles of 

 plant succession and a digest of methods for investigating successional 

 phenomena. A very full historical review of the development of 

 ecological studies is a welcome addition. In the analysis of the causes 

 of succession they are classified into topographic, erosion, deposit, ele- 

 vation and subsidence, edaphic, climatic, biotic and "ecesic causes," 

 under which later name aggregation, migration, ecesis, competition, 

 and invasion are cited. It would seem faulty, in nomenclature at least, 

 to group ecesis under ecesic causes as a branch. In the way of innova- 

 tions of nomenclature Mr. Clements has no equal, and the present 

 volume is rich in this respect. 



Classification is prominently discussed. Plant communities are 

 classified by "serai" and climax units, the former being the dynamic 

 phases of development, the latter a static condition. The latter, the 

 climax units, are classified besides in those classes with which we have 

 been familiar, namely, associations, consociations (characterized by a 

 single dominant species), societies (within an association), into clans, 

 local aggregations of secondary species within the preceding units. 

 Serai, or developmental units, are named analogously to the climax 

 units, the associes, consocies, colony, the difference from the climax 

 units being merely their temporary character. The colony is an initial 

 community of two or more species, resembling the clan in the limited 

 size. Family is reserved for a group of individuals of one species. 



