240 Baroh Humboldt on tJie Strticture and Action of Volcanoes. 



electro-magnetic intensity, or the communication between the 

 internal and external parts of the globe. 



When, in the primitive world, the deeply fissured crust of the 

 earth exhaled heat by these apertures, perhaps during many 

 centuries, palms, arborescent ferns, and the animals of warm cli- 

 mates, lived in vast expanses of country. According to this sys- 

 tem of things, which I have already indicated in my work en- 

 titled Essai Geognostique sur le Gisement des Roches dans les 

 deux Hemispheres, the temperature of volcanoes is the same as 

 that of the interior of the earth, and the same cause which now 

 produces such frightful ravages, would formerly have made the 

 richest vegetation to spring in every zone, from the newly oxi- 

 dised envelope of the earth, and from the deeply fissured strata 

 of rocks. 



If, in order to account for the distribution of the tropical 

 forms that occur buried in the northern regions of the globe, it 

 is assumed that elephants covered with long hair, now immersed 

 in the polar ice, were originally natives of those climates, and 

 that forms resembling the same principal type, such as that of 

 lions and lynxes, may have lived at the same time in very dif- 

 ferent climates, such a mode of explanation would yet be inap- 

 plicable to the vegetable productions. For reasons which ve- 

 getable physiology discloses, palms, bananas, and arborescent 

 monocotyledonous plants, are unable to support the cold of the 

 northern, countries ; and in the geognostical problem which we 

 are here examining, it appears to me difficult to separate the 

 plants from the animals ; the same explanation ought to embrace 

 the two forms. 



At the end of this memoir, I have added to the facts collected 

 in countries the most remote from each other, some purely hypo- 

 thetical suppositions *. The philosophical study of nature rises 

 above the wants of descriptive natural history ; it does not consist 

 of the mere accumulation of isolated observations. May it one 

 day be permitted to the curious and active mind of man, to dart 

 from the present into the future, to interpret what cannot yet be 

 known with precision, and amuse itself with the geognostical 

 fables of antiquity, which are in our days reproduced under va- 

 rious forms. 



* The facts alluded to do not appear in the Appendix to the Memoir. 



