322 THE REVOLUTIONS OF THE CRUST OF THE EARTH. 



continent which appears to unite all the conditions required to be the 

 seat of the creation of man; while Australia, poor in strata, is equally 

 poor in its organisms, which all appear to be the remnants of past ages. 



Everything in nature is intimately connected; the mineral kingdom is 

 a condition of the vegetable, and the vegetable of the animal. And 

 even within the animal kingdom there are creatures whose existence 

 involves as a condition the destruction of other animals. Plants cannot 

 exist for a long time alone upon the surface of the globe; for finding no 

 limit to their growth and extension, and not giving back to the atmos- 

 phere the carbon they are obliged to draw from it, the latter element 

 would in time be exhausted and they would perish. But nature has 

 created the herbivores who, in consuming and digesting the alimentary 

 plants, hasten in the first place their decomposition, which takes place 

 slowly only under the action of the air, and besides restore to the latter 

 by respiration the carbonic acid indispensable to the vegetable kingdom. 

 The herbivores, in their turn, would compromise their existence by de- 

 stroying the plants which serve them as food, if nature had not imposed 

 limits upon their multiplication by creating for them implacable and 

 sanguinary enemies. 



We have already examined in what manner the vegetable kingdom, 

 seat of the cosmic forces, is in relation to the activity of these forces, 

 which have modified the surface of the globe; it remains to be seen in 

 what way the appearance of animals and vegetation influences the organ- 

 ization of the terrestrial crust. 



Plants are, Okeu* observes, organisms suspended between the earth 

 and the sun, or, if you will, between darkness and light, whose appear- 

 ance has as a condition the influence of the central luminary of our 

 planetary system upon the earth. In fact, without light, plants fade and 

 die, while in the ardent rays of a tropical sun and under the influence 

 of the humidity of these warm regions, favorable to them but fatal to 

 the human race, they develop those beautiful forms and brilliant colors 

 which constitute the ornament of equatorial regions. 



Some savans have supposed that the aurora borealis may at some 

 period have supplied the place of solar light, and in consequence the 

 growth of plants have extended over all parts of the globe. It is prob- 

 able that the chemical activity of the earth, indubitably greater at the 

 periods when organisms were produced, gave more importance to this 

 electro-magnetic phenomenon ; but notwithstanding this probability, we 

 dare not affirm its influence upon organisms, not knowing the time of 

 the appearance of organized beings, nor the period when the rupture of 

 the cloudy envelope dissipated the darkness which covered the earth. 

 Whatever may have been the source of light, we see that the conditions 

 of existence must have been very uniform, since the same fossil-remains 

 are found at the equator as in the polar regions. The submarine forests 

 of the shores of Greenland, and the coal-beds of the islands of Disco 

 * Tr. Bromme, Atlas zu A I. v. Humboldt's Kosmos, p. 106. 



