94 THE JOUllNAI, OL' JiOl'ANV 



advantage that it shares with the ordinary word series. We are 

 inclined to agree with these contentions — at any rate, the author 

 leaves no term without an adequate and clear explanation. The second 

 chapter comprises a most useful " General Historical Sununary," 

 condensed into twenty-two pages, from King's work in 1685 on the 

 boo-s and loughs of Ireland, to that of MacDougal and others, as late 

 as 1914. This summary, one feels, lies in the background throughout 

 the remainder of the book ; conformably with the wide range of the 

 author's treatment of his subject, he is generous in his attention to 

 the work of every labourer in the ecological field, and the mark that 

 he has left upon the record of ecological, research. In this connection, 

 the Professor lays well-merited stress upon the work of Dr. C. E. 

 Moss, without which more than one cha])ter in the modern science 

 of Ecology would remain unwritten. The third chapter, " Initial 

 Causes," gives a physiographical account of the formation of bare 

 areas ; the ground is cleared, so to speak, of all plants, to make a fair 

 start. The titles of the next two chapters, IV. " Ecesic Causes " and 

 V. " Reactions," tempt us to suspect Professor Clements of a weak- 

 ness for new words. Sere and its relations we learn to forgive, if not 

 to love, for necessity's sake ; but the titles of the chapters in question 

 excite our wonder as to what they are about — a poor recommendation 

 for a title. "Ecesis," we learn, is derived from oUos, a house, and 

 means "the adjustment of the plant to a new home " — a meaning 

 that would have served admirably as the title of Chapter IV. ; ]ust as 

 " the effect of the plant or community upon its habitat" — the meaning 

 of "Reaction "in the present connection — would have been an excellent 

 title for Chapter V. These two chapters cover a large tield — including 

 mio-ration of plants, competition, invasion, etc., on the one hand, and 

 soil-formation and structure, soil-organisms, the light-, air-, water- 

 factors, etc., on the other. The matter, however, is so judiciously 

 condensed that the space occupied is in no sense out of balance with 

 the rest of the work. We venture at this point to urge that the 

 author has made too little use in the text — especially in this part — of 

 the bibliography with which he is evidently extensively familiar, and 

 of which he gives us a fair, but by no means exhaustive," sample in a 

 catalogue of twenty-five pages at the end. 



A sixth chapter brings us to the last stage — " Stabilization and 

 Climax" — in the history of the formation ; and, at page 111, we enter, 

 with Chapter VII., upon the "Structure and Units of Vegetation." 

 This is an admirable resume of the various concepts of standard 

 authorities — Grisebach, Drude, Moss, Schroter, Gradmann, and 

 Warmino-, — and is in the best historical manner of Moss in the New 

 Phi/toloqist (ix. 18; 1910), whom he quotes constantly and at con- 

 siderable length. Chapter VIII., on " Direction of i)evelo])ment," 

 introduces us to the finished article ; Chapter IX. deals with the 

 " Classification of Seres." This is largely original, the author being 

 himself responsible for the first system of classification, in his 

 Development and Structure of Vegetation. Chapter X. begins the 

 concrete examples of formations — " Climax Formations in North 

 America." Although his own work in this field must be very exten- 

 sive, the writer makes but little allusion thereto ; but w^e recognize 



