FOREWORD 



Impressed with the significance and value of Dr. Wulff's Russian 

 text, which was published in 1932 and again in a slightly revised edi- 

 tion in 1933, I then suggested to him the desirabihty of an EngHsh 

 translation in order that his views might be made more generally 

 available to a wider pubHc. The present volume, revised and brought 

 up to date by Dr. Wulff, as far as war conditions permitted him to do 

 so, has been excellently translated by Miss Elisabeth Brissenden, work- 

 ing in close association with Dr. Wulff in Leningrad. It constitutes 

 the first part, covering general and theoretical problems, of a projected 

 three volume work on historical plant geography. The second part, 

 devoted to a History of the Floras of the World, was completed and, 

 at the outbreak of the present war, ready for publication under the 

 auspices of the Academy of Sciences of the U. S. S. R. in Leningrad. 

 The third part, dealing with the changes in floras caused by man's 

 activities, is in the course of preparation. It is to be hoped that after 

 these two volumes are published, English versions of both may appear 

 corresponding to this one. 



The present volume consists of eleven chapters opening with one 

 covering the scope of the subject, the relationships to allied sciences, and 

 methods of investigation, and closing with an excellently prepared one 

 on the concept of floral elements. Between these two chapters, in much 

 detail, is considered the history of the science, areas: their types and 

 origins, parallelisms in the geographical distribution of plants and ani- 

 mals, artificial and natural factors in relation to the geographic dis- 

 tribution of plants, migrations of species and of floras and their causes, 

 and the historical causes for the present structure of areas and the 

 composition of floras. 



Thus in this single volume students and investigators will find as- 

 sembled in one place a great amount of well coordinated data, pre- 

 sented in a lucid manner, that should greatly lighten their burdens, and 

 act as a stimulant to further investigations. Much work remains to be 

 done and some of the theories discussed need further testing through 

 the laborious process of assembling further details. The publication of 

 this volume in English now makes Dr. Wulff's views very generally 

 available to a wide public. The author, the translator, and the pub- 

 lisher deserve sincere thanks, for the present volume is a mine of 

 logically and authoritatively discussed information on the subject. 



Dr. Wulpf's enthusiastic adherence to the Wegener hypothesis will not be accepted 

 by all plant geographers and geologists; many, in fact, are strongly opposed to it. Al- 

 though it is interesting to note that Wegener's theory has recently enjoyed support in 

 geological circles (see Sir Thomas Holland's recent Bruce-PreUer lecture on the problems 



