20 T O R R E Y A 



nesium rocks? Does age explain why the spectacularly endemic Cupressus ma- 

 crocarpa of the granitic headlands of Carmel Bay stops abruptly at the contact 

 between the Montara granite and the Monterey shale ? The fact that the great 

 majority, if not all, of the oceanic islands rich in endemics are made up either of 

 volcanics or are rich in highly mineralized metamorphics is no chance relation- 

 ship explainable solely on the bases of age and isolation. I do not wish unduly 

 to minimize the role of youth and old age in endemism, but I am suspicious 

 that their role may be much less significant than the literature would lead one 

 to suppose. If this relationship between endemics and local habitat is as real as 

 it appears, then such problems may well be explained from the genetic point of 

 view. The logical approach is first to attempt to explain the occurrence of en- 

 demics in situ in terms of the local habitat and of such genetic phenomena as are 

 so superbly treated in parts four and five of this book. Should this fail, then the 

 gods of theory and logic might be invoked. 



I doubt if anything is gained by a definition of endemism that limits the 

 term to distributional patterns of one area. So many of the phenomena of dis- 

 continuous distribution are so intimately linked with the causes of endemism 

 that they are inseparable in many of their aspects. 



After the able presentation by the author of the various aspects of what, in 

 the past, has been termed the "science of area" and newly christened "areogra- 

 phy," I think that we are justified in abandoning many of the ideas expressed 

 in the papers reviewed by the author in this field. They are too irrelevant and 

 on too precarious a scientific foundation. It is a subject in which generalizations 

 are probably futile. This is especially true of many concepts of area and of 

 dispersal and dispersal mechanisms. Distribution is intimately linked with or- 

 ganic processes subject to orderly physiological and physical law. History is 

 the record of the sequence of very definite events in any given area. The vagaries 

 of mass interpretations of area are too great for their safe application to the 

 interaction of these rather complicated phenomena with the event's of history. 



In reading the discussion of "Evolution and Plant Geography" one cannot 

 escape the feeling that the facts of the nature of species transcend immeasur- 

 ably the importance of defining species. It would appear that the more one 

 knows about speciation and species behavior the less significant is a definition 

 that could include all types of species. The problems of speciation in the various 

 parts of the plant kingdom are too diverse to permit of such a definition. In this 

 part of the book, as well as in the part dealing with polyploidy, the facts of gene- 

 tics and polyploidy are so ably treated that it seems almost presumptuous to cri- 

 ticize. Yet the science of plant geography would have been better served had 

 the author summarized frequently in terms of methods of application and values 

 to the plant geographer. For the moment, at least, the plant geographer seems 

 to have been forgotten. To illustrate my point, in the general subject poly- 

 ploidy, even under the heading "Geographic aspects of polyploidy," nowhere 



