BOOKS AND WRITERS 



Five chapters, covering some 200 pages, are comprised 

 in the second and concluding volume of Dr. William F. 

 Ganong's "Textbook of Botany for Colleges," issued by the 

 Macmillan Company. Four of these chapters are devoted 

 to the phytogeny of Thallophytes, Bryophytes, Pteridophy- 

 tes, and Spermatophytes, respectively, and the fifth. dis- 

 cusses the classification of plants from an ecological view- 

 point. In the pages devoted to phylogeny, the divisions, 

 classes, and orders of plants are introduced in the customary 

 sequence and their essential features carefully described 

 together with much information regarding the ecology and 

 distribution of typical forms which must be exceedingly 

 valuable to those desiring a comprehensive view of plant 

 relationships. In the ecological classification of plants, the 

 author has departed somewhat from the usual textbook 

 treatment and, instead of emphasizing the plant association, 

 has paid more attention to growth and habit forms. The 

 vegetation of the world is placed in seven divisions: hydro- 

 phytes, mesophytes, tropophytes, helophytes, xerophytes, 

 halophytes, and oxalophytes. The tropophytes are those 

 plants usually classed as mesophytes which are exposed to 

 xerophytic conditions for part -of the year. The helophytes 

 might be described as spermatophytes and others which 

 have taken to an aquatic or semi-aquatic life and are not 

 true hydrophytes, such as the algae. In view of the simi- 

 larity in sound between helophyte and halophyte, the re- 

 viewer suggests the term paludophyte for the former. It 

 has essentially the same meaning. The oxalophytes, as 

 may be surmised, are the plants of bogs and other undrained 

 areas where the soil or soil-water is acid. The first volume 

 of Dr. Ganong's book, issued last year, is an extended and 

 particularized account of the structure, morphology, and 



