122 SKETCH OF THE LIFE AND ACHIEVEMENTS 



above 6,000 kinds of new plants, observations 

 upon which enabled Humboldt to open new 

 avenues with regard to the laws of plants and 

 their relation to the earth. The great work, 

 " Essai sur la Geographic des Plantes," and 

 a still more elaborate account in the " Prolego- 

 mena de Distributione Geographica Plantarum 

 secundum coeli temperiem et altitudinem mon- 

 tium," establish in a striking manner, enriched 

 by manifold experience, the importance of geo- 

 graphy with regard to botany, and the imme- 

 diate relation of the geography of plants to 

 their history and the science of climate.* It 

 shows, furthermore, how the number, the rela- 

 tion, and the local distribution of plants must of 

 necessity vary in accordance with general laws 

 in the different zones, from the pole to the 

 equator ; from the depth of mines and the 

 bottom of the sea, to the summit of mountains 

 covered perpetually with snow ; relatively to the 

 geographical position of the locality, and the 

 condition of the environs. The special history 

 of the new discoveries in botany Humboldt 

 was obliged to leave to his fellow-labourers. 



* See the profound essay of Mr. William Hopkins, of 

 Cambridge, "On the Causes of Changes of Climate at 

 Different Geological Periods," Quart. Journ. Geol. Soc. 

 London, vol. viii. p. 56. 



