ig2o] CURRENT LITERATURE 185 



of the unit are respectively (1) of the same species, (2) of different species but 

 of the same growth forms and of similar aspect, and (3) of different species and 

 various growth forms presenting different series of aspects but united into an 

 ecological unit in a single habitat by fixed correlation. This last grade of 

 synusium corresponds very nearly with the "association" of most authors. 

 Similar synusia are grouped as "isocies." For the topographical unit he adopts 

 the w r ord "biocoenose" (or biocoenosium) , and uses it for the vegetation of a 

 unit habitat. Biocoenosia of different regions which are compounded of 

 isocies are called "isocoenosia." 



The author rejects all attempts to classify vegetation units upon dynamic 

 lines. He also gives a new classification of life forms, based largely upon the 

 Raunkiaer system, but more extended and including animals. It is safe 

 to predict that such revolutionary changes as those urged by Gams, even if 

 they are logically conceived, will not be acceptable to the ecologists of America, 

 and, judging from the criticism of the scheme by Pavillard (19 19), they will 

 meet with no greater favor in France.— Geo. D. Fuller. 



Statistical methods in ecology. — It seems appropriate that from among 

 the students of that father of modern ecology, Eugene Warming, should 

 come a leader of perhaps the most promising line of advance in the ecology 

 of today. Raunkiaer more than any other has opened the way for the 

 introduction of quantitative methods in the study of vegetation. His method 

 of comparing the floras of different regions by means of a numerically expressed 

 biological spectrum, 8 and of evaluating the mesophytism of a habitat by leaf 

 classes, 9 have been noted in this journal. The latter method of estimating 

 vegetation was made more familiar to American ecologists by the transla- 

 tion of Fuller and Bakke, 10 who also included in their article a summary of 

 a statistical method that had been familiar to Danish readers for some years. 11 

 In a more recent article? Raunkiaer 12 has summarized the material of his 

 former contributions, and has been able to show something of their applica- 

 tions to the solution of ecological problems. His statistical or valence method 

 consists in determining the relative abundance of the different species compos- 

 ing a plant community of definitely limited extent, called by him a "forma- 

 tion," although more nearly equivalent to an association as understood by 

 Vmerican ecologists. This determination is made by taking a census of a 



1 



Box. Gaz. 51:309-310. 1911. • Bot. Gaz. 63:242. 1917. ? 



10 Fuller, Geo. D., and Bakke, A. L., Raunkiaer's life-forms, leaf-size classes, 

 and statistical methods. Plant World 21:25-37, 57-63. fig. r. 1918. 



Raunkiaer, C, Formations undersgelse og Formationsstatistik. Bot. Tidskr. 

 30:20-132. 1909. 



11 



12 



-, Om Valensmetoden. Bot. Tidskr. 34:304-311. 1917. 



Recherches statistiques sur les formations vSgetales. Det. Kgl. 



Danske Videnskabernes Selskab. Biol. Meddeieser. I 3: PP- So. figs. j. 1918. 



