58 REVIEWS. 



tribution of genera and of families is illustrated, and this division of the 

 subject concludes with some general remarks on the changes which take 

 place in the habitats of families, and the origin and derivation of these 

 groups. Our limits do not permit us to enter into these subjects, which 

 occupy ten chapters of the Essay. 



Nor can we do more than indicate the subjects contained in the remain- 

 ing portion, called by the author Botanic Geography, in distinction to Geo- 

 graphic Botany. Seven chapters are devoted to this section, which com- 

 prises the following items : — General Characters of Vegetation ; Com- 

 parisons between different countries with respect to the proportion of 

 Dicotyledons to Monocotyledons, and a comparison with respect to the 

 families most numerous in species, and to the families most characteristic 

 of the country. Then follows a chapter on the variety of vegetable forms 

 in different countries and in the entire globe ; the division of the surface of 

 the globe into natural botanical regions ; and lastly, the vegetation of 

 different countries is considered in regard to the probable origin of their 

 species, genera, and families. In this last chapter the ingenious views of 

 Edward Forbes iu relation to the origin of the Mediterranean species, which 

 occur so abundantly in the West of Ireland, are favourably noticed. 



We must now conclude our hasty sketch, warmly recommending these 

 volumes to the careful study of all persons interested in the subjects of 

 which they 1 real. From the imperfect abstract we have given it will be 

 evident that the questions of the climatical relations of plants are treated 

 with great minuteness, with much learning and research, and the material 

 ably and laboriously worked up. It is a work which will at once take 

 rank as a text-book, to be referred to, not as a complete essay, exhausting 

 the subject, but as a storehouse of information, uniting within a moderate 

 compass most of the observations yet recorded, and serving, therefore, as 

 a stable basis for further research. The subject of Botanic Geography, so 

 far from being exhausted, is only yet in its infancy, and no doubt many of 

 its facts will be read differently hereafter ; but we think that the principles 

 stated and advocated in the present treatise will, as a whole, stand the test 

 of time. 



W. H. H, 



