Apkil 6, 1917] 



SCIENCE 



339 



ney long distances, many from the south and 

 the west, to attend the New York meeting. 



The relation to agriculture of considerable 

 parts of the programs of various sections and 

 affiliated societies seems increasingly greater 

 with each succeeding meeting. Perhaps it is 

 because our interest is broadening. Perhaps it 

 is because the investigation in agriculture is 

 leading more and more deeply into the realm 

 of the sciences. And undoubtedly it is because 

 interest in these problems is becoming more 

 widespread, for the problems of agriculture are 

 now attracting the attention of very many men 

 and women identified with nonagricultural in- 

 stitutions. The biological chemists, the various 

 botanical organizations, the entomologists, the 

 zoologists, the geneticists, the ecologists, all 

 had papers of immediate import to agricultural 

 investigation. Indeed, there were so many of 

 these contributions and discussions that the 

 dilficulty was to hear more than a small part 

 and to make a selection. — Experiment Station 

 Record. 



SCIENTIFIC BOOKS 



Plant Succession. An Analysis of the Devel- 

 opment of Vegetation. By Prederic E. 

 Clements, Carnegie Institution of Wash- 

 ington, Publication Number 242, Washing- 

 ton, D. C, 1916. Pp. xiii + 512, 61 half 

 tone plates of two to three figures each, and 

 51 figures in the text. 



For nearly a quarter of a century the author 

 of this large and attractive volume has been 

 investigating numerous problems in the field 

 of phyto-eeology and related subjects as he 

 has found them in the great out-of-door labo- 

 ratory of western United States. This area 

 is particularly stimulating for such work since 

 so many of the natural life phenomena have 

 been preserved to the present in nearly their 

 original conditions. During these years the 

 author has been favored with unusual facil- 

 ities for the conduction of his investigations. 

 Because of these facts, as well as because of 

 the well-known leadership which American 

 ecologists enjoy, this latest work from Clem- 

 ents will attract the attention of botanists and 

 biologists in general throughout the world. 



The reader must understand that this work 

 is not in any sense a treatise on general plant 

 ecology. It represents a careful examination 

 of the facts and principles of plant succession, 

 an analysis of the development of vegetation 

 in the past as well as the present, together 

 with a digest of the methods for investigating 

 successional phenomena. 



The subject-matter of the monograph is ar- 

 ranged in fifteen subdivisions or chapters. In 

 Chapter I. the author rewrites his rather 

 familiar views as to the fundamental nature 

 and causes of succession. He points out that 

 " the developmental study of vegetation rests 

 upon the assumption that the unit or climax 

 formation is an organic entity." As a living 

 entity this unit arises, develops, matures and 

 eventually disappears. All such entities or 

 formations develop as a result of succession 

 which may occur again and again in the his- 

 tory of each climax unit. The most striking 

 external featiu-e of succession lies " in the 

 movement of populations, the waves of inva- 

 sion, which rise and fall through the habitat 

 from initiation to climax." 



An excellent historical summary beginning 

 with King (1685) and including the work of 

 twentieth century ecologists is included in 

 Chapter II. This is a valuable summary of 

 the concepts that have helped in shaping 

 modern ideas with regard to plant succession. 



Then follows a long chapter on the causes 

 of succession. " Initial causes " are discussed 

 under the captions: Topographic Causes, 

 Erosion, Deposit, Elevation and Subsidence, 

 Edaphic Causes, Climatic Causes, Biotie 

 Causes, while " ecesie causes " are enumerated 

 as Aggregation, Migration, Ecesis, Competi- 

 tion and Invasion. This chapter is followed 

 by a study of stabilization and the develop- 

 ment of the final or climax community. 



The structure and units of vegetation are 

 treated at length and the views of various 

 ecologists upon these subjects summarized. 

 One of the most interesting, as perhaps most 

 valuable, parts of the book is the attempt of 

 the author to focus attention more sharply 

 than has ever been done before upon the fact 

 that plant communities may and should be 



