THE CONTINENTAL FLORA OF SOUTH SWEDEN 225 



Lector C. S. Fearenside of Stockholm, wlio has revised and in part supple- 

 mented the translation of this work, I have also to thank for his advice and 

 suggestions with regard to typographical details. 



Chapter L 



A few words about the history of taxonomic phytogeography and 



its present object and principles. 



When, at the beginning of the nineteenth century, phytogeography came up 

 as an independent branch of botany, the distribution of species became a subject 

 of keen interest. The investigators who paved the way for the new branch of 

 science began to sum up the various single observations that had been made 

 earlier relative to the distribution of species, and also to treat them from more 

 general points of view. Men's views were widened with the aid of the numerous 

 research expeditions to parts of the world thitherto unknown. 



The lines along which the phytogeographers of that time were working are 

 excellently brought out in the title of a work which perhaps may be designated 

 as fundamental for all work achieved in the domain in question, viz. Alexander 

 von Humboldt's »De distributione geographica plantarum secundum coeli temperiem 

 et altitudinem montium» (Paris 1817). Consequently the object was to find out 

 the correlation between the distribution of species on the one hand and the 

 climate, more especially the temperature, on the other. 



At the same time meteorology was in the midst of a grand development. The 

 larger material in the way of temperature observations from widely separated 

 parts of the world that was now being gradually placed at the disposal of scien- 

 tists was subjected to a comparative study, isotherms could be constructed, and 

 some definite idea of the general laws of the variations of temperature on the globe 

 was obtainable. 



The object of phytogeography was to tr)' to explain the main features of the 

 distribution of species and the general character of the flora by means of the 

 knowledge gained about climate, especially about the variations of temperature. 

 Later on, efTorts were made to explain even more detailed problems regarding the 

 distribution of species, especially with the help of the climate. 



As other fundamental works on taxonomic phytogeograph)- in this short intro- 

 duction to be mentioned alongside the work of Humboldt are C. L. Willdenow's 

 »Grundriss der Krauterkunde», 1792 (pp. 345 fT.), where we already find indicated 

 several of the guiding lines for the research work of later times; and several works 

 by Goran Wahlenberg (»Flora lapponica^ 18 12, »Tentamen de vegetatione et cli- 

 mate Helvetiae septentrionalis» 1S13, »Flora Carpatorum principalium» 18 14). 



