278 The Plant World, 



ent is the core of the volume, being at once the part for w hich 

 the author planned his preliminary studies and the part in 

 which he approached his most difficult undertaking. He has 

 made a digest of the descriptive literature \\ hich is available,- — • 

 a most prodigious and thankless task, — to which he has added 

 his own observations in several portions of the United .States, 

 Mexico and the West Indies. The phytogeographical subdi- 

 vision of North America b\ Harshberger is the first that has been 

 made by an American w liter, and is, as we might expect, more 

 detailed and more natural than the partitions made by Drude 

 (Atlas dcr Pflanzenverbreiiung, 1887) and by Engler {Die Pjlanz- 

 engeographische Gliederung Nordamerikas, 1902), to mention 

 only the best of the previous attempts. Harshberger's map of 

 North America has been prepared so as to depict the floristic 

 areas, but comes near to being an equally good representation 

 of the regions of vegetation as well. This circumstance is 

 partially inherent in the facts and partiallv an index of the 

 extent to \^ hich floristics has been influenced by physiological 

 plant geography in recent years. The map is not quite so de- 

 tailed as its scale would have permitted it to be, in fact there are 

 a number of minor particulars in \\ hich Engler's map is superior 

 to it. 



A work of this character and magnitude can be accomplished 

 only by a heavy reliance on the observations of other men, not 

 only entailing a dependence on their accuracv, but an equally 

 important one on their ability to see the things that are most 

 significant. Superadded to this is the necessity that the com 

 piler see in each paper the features and facts that the author 

 considered most important. The Survey has suffered in some 

 respects from these difficulties, inherent in such a great under- 

 taking, but it is nevertheless an extremely valuable volume, 

 rising far above its errors of detail to give a delineation of the 

 botanical features of our continent which will be very useful 

 to American botanists, and, by virtue of its ])lace in Die Vege- 

 tation, V ill stimulate European interest in our vegetation. 



The editors of Die Vegetation der Erde should not escape 

 without censure for having alloted the whole of North America 

 to a single volume of their series. They have driven the author 



