OF PLANTS AND ANIMALS. 847 



ground above the level of the sea in mountains, and by the 

 distance from the equator in the plains. Menzel, in an 

 unedited flora of Japan, used almost accidentally the ex- 

 pression " geography of plants," and the same expression is 

 found in the fanciful but graceful work of Bernardin de St.- 

 Pierre, entitled ' ' Etudes de la Nature/' A scientific treat- 

 ment of the subject, however, only commenced when the geo- 

 graphy of plants was brought into close connection with the 

 study of the distribution of heat over the surface ot the 

 earth; and when, by a classification into natural families, it 

 had become possible to distinguish numerically the forms 

 which increase or decrease in frequency in receding irom 

 the equator towards the poles, and to assign the nu- 

 merical proportion which in different regions of the earth 

 each family bears to the entire mass of the phsenogamous 

 flora of the same region. I regard it as a happy circumstance 

 in my life, that at a time when my views were almost ex- 

 clusively turned to botanical studies, I was led, by the 

 favouring influence of the grand spectacle presented by the 

 mountainous regions of the tropics, where the most varied 

 climates and vegetation are brought into close proximity 

 and contrast, to those subjects of investigation of which I 

 have here spoken 



The geographical distribution of animals, on which Bnffon 

 first put forward general views and in many instances just 

 ones, has of late years benefited greatly by the progress made 

 in the study of the geography of plants. The isothermal 

 curves, and particularly the isochimenal curves, whether of 

 latitude or of elevation, coincide with the limits which species 

 of plants and of animals which do not wander far from their 



