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REVIEWS 



Spalding's Distribution aid Movements of Desert Plants >i'- 



The author has divided his problem into seven divisions, under 

 as many headings. Five of these appertain to various phases of 

 his problem, the last two are mainly recapitulative. 



Tumamoc Hill and its environs, near the desert botanical 

 laboratory, Tucson, Arizona, was the place chosen where " pro- 

 longed observational and experimental work could be under- 

 taken." The first section of the paper (pp. 5-27. //. 1-12) is taken 

 up with a clear and logical account of the plant associations and 

 habitats as they have appealed to the author. Appended to this 

 is an account of the lichens of the region, written by Dr. Bruce 

 Fink. 



Leaving the section on plant associations and habitats which, 

 though valuable, is necessarily becoming more and more stereo- 

 typic in each succeeding ecological paper, we come to the most 

 interesting part of the whole work. In this second chapter (pp. 

 29-66. p/. ij-2^), the author gives an account of the local dis- 

 tribution. He writes : " Dealing more in detail with constituent 

 species of the associations, the attempt to trace cause and effect 

 is carried a step farther. Certain species have been carefully 

 mapped and their habits have been more thoroughly studied 

 with reference to differences of soil and aspect." 



The species selected for this study are plants " with a remark- 

 able definiteness of habitat preference "; they are Encelia farinosa, 

 Larrea tridentata, Cereus (why not Carnegiea?^ giganteus , Cercidiuni 

 Torreyamwt, and Prosopis velutina. A distribution-map for each 

 of these species is included, and they form a series of invaluable 

 notes. Each map is practically a graphic census of the indi- 

 viduals of the species under discussion. Nothing could have 

 been found to indicate so well the relative density of these plants. 

 The various soil formations are critically studied, and following 

 as they do the various distribution-maps mentioned above, they 

 are at least a suggestion of the factors the author credits with the 



*Spalding, V. M. Distribution and Movements of Desert Plants. Pp. 1-144. 

 pi. 1-31. 22 Oct. 1909. Carnegie Institution of Washington, Publication No. 113. 



