REVIEWS 17 



Plant Geography 



Foundations of Plant Geography. By Stanley A. Cain, xiv + 556 pages. Harper and 

 Brothers. 1944. $5.00. 



The spirit of science demands that every theory be forced to justify its 

 existence and that our philosophy be constantly revised that it may always be 

 in keeping with the advances in our knowledge. "The Foundations of Plant 

 Geography" by Stanley A. Cain attempts to reconcile the thinking in plant 

 geography to the very great advances in our knowledge in the several con- 

 tributing fields, and surveys the research methods in these fields. There is 

 brought together in one volume a mass of material representing the significant 

 thought on all sides of the many problems bearing on the dynamics of plant 

 distribution. In some instances the author writes as an able reporter, in other 

 instances he chooses to comment upon or synthesize and review the subject 

 matter. Much of this is done superbly and with a clarity that enables one to 

 evaluate as never before the scientific worth of many of our ideologies. 



The work is divided into five parts, each dealing with a distinct approach 

 to research in plant geography. Part one attempts to orient the reader and pre- 

 sent a resume of previous expositions of the principles of plant geography ; 

 part two deals with what the author terms paleoecology ; part three is termed 

 "areography" and concerns spacial distribution and restriction ; part four treats 

 evolution and speciation and part five elaborates the inter-relations of poly- 

 ploidy and plant geography. There is no attempt at floristic description. The 

 work aims solely at elucidating the principles underlying the dynamics of plant 

 geography. 



By way of orientation the author refers in his introduction to "descriptive 

 plant geography" and to "interpretive plant geography." The first of these is 

 static and furnishes a part of the materials for the second which is dynamic. 

 The rest of the materials of interpretive geography result from integration and 

 synthesis of the more specialized fields of botany. In addition, "physiological 

 plant geography" is frequently mentioned in the text. Apparently the author 

 prefers to give this subject no "more than incidental mention." In many respects 

 this is unfortunate as some of the criticism I would make of the work hinges 

 upon problems that are physiological in scope or in implication. 



In dealing with some previously proposed principles of plant geography 

 and again, in discussing migration and the evolution of vegetation, the author 

 becomes involved between two diametrically opposed concepts as to the relative 

 significance of the means and the extremes of environmental factors in con- 

 trolling the distribution of plants. According to the author, Clements maintains 

 that the means are more significant that the extremes, whereas Mason (your re- 

 viewer) maintains that "in any given region the extremes may be more signifi- 

 cant than the means." In attempting to resolve these divergent points of view, 



