For the student of plant geography, one of the chief merits to be found in this trans- 

 lation is its analysis and discussion of a large amount of continental, especially Russian, 

 literature which would not otherwise be readily available. It will be not less useful for its 

 lucid discussions of the classic concepts upon which much of modern floristic plant geog- 

 raphy is based. On the other hand, students will undoubtedly miss a number of references 

 to American literature which deal with the various subjects that make up Professor Wulff's 

 work. This is particularly true of a number of very recent papers, many of which will be 

 found to add greatly to the argument of the book. The exigencies of transportation during 

 war time have of course made it extremely difficult for students on two sides of the world 

 to keep up with one another's work. It may therefore be suitable to add some notices of 

 papers that are outstanding in the fields they represent. The following paragraphs are 

 not to be considered in any sense complete, therefore, and are offered merely, in accordance 

 with Dr. WuLFP's desires as expressed to the editor of this series, as aids toward the com- 

 pletion of certain chapters of the book. 



The historical and classic phases of geographic botany have had a brief but excellent 

 treatment in "A Short History of the Plant Sciences" by H. S. Reed (Chronica Botanica 

 Co., 1942); while an earlier American paper by E. L. Greene on "Landmarks of Botanical 

 History" (Smithsonian Miscel. CoU., igog), though not cited by Wulff, will yield much of 

 value. With regard to the significance of Alexander von Humboldt as the founder of 

 modern phytogeography, discussed by Wulff on p. 11, the reader wiU find further ma- 

 terial in a recent book by Richard Hartshorne on "The Nature of Geography" (Ann. 

 Ass. Am. Geogr. 29: 171-658, 1939; reprinted in book form with separate paging). 



Some of the criteria for the determination of center of area, treated at some length by 

 Wulff in his third chapter, were outlined many years ago in America by C. C. Adams: 

 "Southeastern United States as a Center of Geographic Distribution of Flora and Fauna" 

 (Biol. Bull. 3: 1x5-31, 1902). Adams' criteria have been critically re-examined and ex- 

 tended by Stanley A. Cain in a paper now in press. 



The problems centering in the origin of geographic areas are, as Wulff makes clear 

 (Chapter IV), closely allied to those of speciation. A number of papers have appeared 

 recently in American biological literature which touch upon these problems, and since they 

 appear to have advanced our thinking considerably, a few of the more important will be 

 cited. Dobzhansky's book on "Genetics and the Origin of Species" (Col. U. P., 2nd ed., 

 1941) contains stimulating discussion of some of the geographic aspects of speciation. Re- 

 sults of the extensive transplant experiments carried on by the Carnegie Institution in 

 California have far-reaching implications for American students of floristic geography. 

 They have been published by J. Clausen, D. D. Keck and W. M. Hiesey in "Experi- 

 mental Studies in the Nature of Species, I. Eilect of varied environments on Western 

 American Plants" (Carn. Inst. Wash. Publ. 520, 1940). Other aspects of the genetical 

 approach to geographic problems are to be found in papers cited below in supplementing 

 Wulff's treatment of migration (Chapter IX). The relation of recent studies of poly- 

 ploidy to geographic problems is noted in papers by Edgar Anderson, "Cytology in its 

 Relation to Taxonomy" (Bot. Rev. 3: 335-50, 1937), and by G. L. Stebbins, "The 

 Significance of Polyploidy in Plant Evolution" (Am. Nat. 74: 54-56, 1940). 



