Geology and Natural History. 345 



showing the floral regions according to Engler. Berlin, 1908 (R. 

 Friedlander & Sohn). — Although the flora of Africa has received 

 a great deal of attention from systematic botanists, especially in 

 Europe, there has been lacking a comprehensive work dealing 

 with the plants of the entire continent. The present volume sup- 

 plies this want, and is intended more particularly for the use of 

 travelers and colonists, giving them the means whereby they may 

 ascertain the names and relationships of the plants they meet 

 with. For this reason it includes not only indigenous plants but 

 also many that have been introduced, especially those that have 

 become naturalized or are cultivated on a large scale. The work 

 first gives a series of keys for the determination of the natural 

 families. This is followed by a full characterization of the fami- 

 lies, under which further keys are given leading to the determina- 

 tion of the genera. The families are arranged according to the 

 widely adopted Engler-Prantl system, and under each family the 

 number of genera and species- represented in Africa is noted. 

 Although many of the generic characters are indicated in the 

 keys, the genera themselves are not formally described, and no 

 attempt is made to enumerate the peculiarities of the species. It 

 is only in the case of economic plants, in fact, that the names of 

 the species are given. In the numerous plates at the close of the 

 volume a characteristic species from each of the more important 

 families is represented. In an interesting summary the author 

 estimates the number of phanerogams for the whole world at 

 136,000, of which no fewer than 39,000 are accredited to Africa. 



a. w. E. 



14. Schwendeners Vorlesungen uber mechanische Probleme der 

 jBotanik, gehalten an der ZTniversitdt Berlin : by Dr. Carl 

 Holtermaxn. Pp. vi, 134, with portrait of Schwendener and 90 

 text figures. Leipzig, 1909 (W. Engelmann). — Professor Schwen- 

 dener's lectures on the mechanical problems of botany give in a 

 condensed form the results of his important investigations in a 

 field of botanical science which he has made peculiarly his own. 

 These lectures have been edited by his former pupil, Professor 

 Holtermann, and are now made accessible to a wider circle of 

 botanists through the publication of the present work. Among 

 the topics treated, the following are perhaps the most important : — 

 the mechanical system (skeleton) of plants, the theory of leaf 

 arrangement, the upward flow of sap, the stomata, the twining 

 of plants. Wherever possible the mechanical properties of the 

 structures discussed are expressed by mathematical formulas. 



a. w. E. 



15. Plant Study, with Directions for Laboratory and Field 

 Work; by W. H. D. Meiek, Superintendent City Schools, 



Havana, Illinois. Boston, 1909 (Ginn & Company). — A series 

 of loose sheets, held together in a binder ; 36 of the sheets give 

 directions for laboratory exercises, abundant space being left for 

 notes. The exercises are apparently designed to prepare the stu- 

 dent for the analysis of plants, the last part of the series includ- 

 ing a number of blanks for plant descriptions, spaces being left 

 for the specimens themselves. a. w. e. 



