214 NOTICES or BOOKS. 



Bruce mentions the fact of the stem of the Iksete being perennial; 

 in that respect diflFering remarkably from the common Bananas, which 

 die immediately after ripening their fruit. The plant from which Bruce's 

 drawings were made, he assures us, was ten years old. 



NOTICES OP BOOKS. 



Geographte Botanique Eaisonn^e, ou Exposition des Faits prin- 



cipaux et des Lois concernant la Distribution GeograpTiique des Plautes 

 de Vepoque actuelle; par M. Alph. de Candolle. 2 vols. 8vo. Paris. 



{Continued from p . 191.) 



The question whether islands have fewer or more species than equi- 

 valent areas on continents, has long occupied the attention of natural- 

 ists, Von Buch holding that they have fewer, Schouw that they have 

 more. M. de Candolle finds, as was to have been anticipated, that the 

 extent of insular Floras varies with their proximity to the great conti- 

 nents. When so close that they may be regarded as almost a part 

 of a continent, as Tasmania is of Australia, or Ceylon of the peninsula 

 of India, there is no marked difference between the numerical propor- 

 tions of the insular and continental Floras ; but in the case of islands 

 far removed from continents, their Floras are generally very poor in 

 species, except those in the northern regions. 



Under conjectural estimates of the total number of flowering plants 

 on the smface of the globe, M. de Candolle enters into an extremely 

 careful and* close analysis of all the materials within his reach, and 

 arrives at the conclusion that the number may lie about 250,000, using 

 the term species in the sense intended by Linnaeus ; and 400,000 to 

 500,000, in the sense adopted by many modern botanists. The former 

 number greatly exceeds our own estimate ; this we regret that we 

 are not prepared to lay before the reader, but hope, by means of a 

 cai'eful analysis, of the Floras of some large, well-explored tropical 

 areas (much larger than have hitherto been treated of), to offer some 

 more definite data for the foundation of such an estimate than have 

 hitherto been published. From the numerous tables M. de Candolle 

 has given of the known and supposed number of species inhabiting 

 certain countries, it is evident, as we have before indicated, that his 



