THE WONDERS OF VEGETATION. 281 



the earth was covered with vegetation, these few spe- 

 cies had a very monotonous appearance. The modern 

 naturalist who could behold the earth as it then was, 

 would be struck by the vast expanse of forests which 

 covered the earth wherever the water had receded, 

 but also by the melancholy uniformity of the trees 

 forming these interminable woods and the absence of 

 all life. Not only were there only a few of the 200,000 

 species in existence which we now admire in their 

 matchless variety of form and color, but the diversity 

 produced by climate, from the tropical heat near the 

 equator to the eternal ice of the Polar Sea, was want- 

 ing, since climate itself was as yet an unknown feature 

 of our globe. The heat of the sun had little effect 

 by the side of the intense heat of the earth itself. 

 Hence, even now the fossils of animal as well as vege- 

 table life of those days are invariably the same, 

 whether they are found in the Arctic Zone or in the 

 Tropics. One vast uniform forest literally covered 

 the whole globe. The heat at the poles, drawing its 

 power from the internal heat of our earth, was then 

 at least equal to the highest temperature now known 

 in the Torrid Zone. 



Besides the. simple horse-tails and ferns, of which 

 the humble representatives surviving in our day 

 give us a better idea than any design could do, 

 the primitive world possessed a few equally simple 

 varieties of plants, which have since entirely disap- 

 peared from the surface of the earth. Zimmerman 

 assures us that there are no plants now in existence 

 like those extinct vegetables. 



