GEOGRAPHY OF PLANTS. 347 



together like the pipes of an organ — Avicenniae and mangroves 

 in the tropics — and forests of Coniferse and of birches in the 

 plains of the Baltic and in Siberia. This mocle of geographical 

 distribution determines, together with the individual form of 

 the vegetable world, the size and type of leaves and floAvers, 

 in fact, the principal physiognomy of the district ;* its charac- 

 ter being but little, if at all, influenced by the ever-moving 

 forms of animal life, which, by their beauty and diversity, so 

 powerfully affect the feelings of man, whether by exciting the 

 sensations of admiration or horror. Agricultural nations in- 

 crease artificially the predominance of social plants, and thus 

 augment, in many parts of the temperate and northern zones, 

 the natural aspect of uniformity ; and while their labors tend 

 to the extirpation of some wild plants, they likewise lead to 

 the cultivation of others, which follow the colonist in his most 

 distant migration. The luxuriant zone of the tropics offers 

 the strongest resistance to these changes in the natural distri- 

 bution of vegetable forms. 



'Observers who in short periods of time have passed over 

 vast tracts of land, and ascended lofty mountains, in which 

 climates were ranged, as it were, in strata one above another, 

 must have been early impressed by the regularity with which 

 vegetable forms are distributed. The results yielded by tlieir 

 observations furnished the rough materials for a science, to 

 which no name had as yet been given. The same zones or 

 regions of vegetation which, in the sixteenth century. Cardinal 

 Bembo, when a youth,! described on the declivity of iEtna, 

 were observed on Mount Ararat by Tournefort. He ingen- 

 iously compared the Alpine flora with the flora of plains situ- 

 ated in different latitudes, and was the first to observe the in- 

 fluence exercised in mountainous regions, on the distribution 

 of plants by the elevation of the ground above the level of 

 the sea, and by the distance from the poles in flat countries. 

 Menzel, in an inedited work on the flora of Japan, accidental- 

 ly made use of the term geography of plants ; and the same 

 expression occurs in the fanciful but graceful work of Ber- 

 nardin de St. Pierre, Etudes de la Nature. A scientific treat- 

 ment of the subject began, however, only when the geography 

 of plants was intimately associated with the study of the dis- 



* On the physiognomy of plants, see Humboldt, Ansichten der Natur, 

 bd. ii., 8. 1-125. 



+ ^tna Dialogus. Opuscula, Basil., 1556, p. 53, 54. A very beauti- 

 ful geography of the plants of Mount ^tna has recently been published 

 by Fhilippi. See Linncea, 1832, s. 733. 



