Picture of Orgmiised Nature, 



343 



hemispheres, according 

 to the law of elevation, 

 by similar markings on 

 the elevations of the ty- 

 pical mountains where it 

 was found {fg). Types 

 might be formed for the 

 printer, representing 

 skeleton maps and sec- 

 tions, such as we have 

 described ; and the situ- 

 ation of the order or 



genus might be filled in >^^^^ aT 



with other types representing dots, so that this description of 

 illustration would cost little more than common printing. The 

 distribution of plants and animals, according to the laws of 

 soil and civilisation, is of much less consequence, and much 

 more easily described and remembered, than their geographi- 

 cal distribution. 



We shall now endeavour to give some idea of the plan 

 adopted by MM. Wilbrand and Ritsen. A correct idea 

 of their picture may be formed by imagining our figures 

 103. and 104. joined in one by the linear. These figures, 

 when joined together, represent an island of mountains rising 

 out of the ocean, with imaginary straight lines radiating from a 

 centre, and imaginary elliptical lines forming parallels above 

 and below the base line of the island. 



The Chimborazo mountain {Jig, 104. b) is the highest in the 

 centre ; the Himalaya mountains of Asia {Jig, 103. c\ upwards 

 of 25,000 ft. in altitude, are the highest to the left ; and the Des- 

 cabezado {Jig, 104. d\ in Chile, is the highest to the right. The 

 snow line, or that which in every part of the globe sets the limit 

 to organised beings, as regulated by latitude, begins at 75° N. L. 

 {fg, 103. e\ and 60° S. L. {Jig. 104./) ; as governed by eleva- 

 tion, it begins under the equator at a perpendicular height of say 

 17,000 ft. {fgs. 103. and 104. g) ; in the 19° N. L. 15,000 ft., 

 in the 35° N. L. 11,000 ft., in the 43° N. L. 8,600 ft., in 62*» 

 N. L. 6000 ft., gradually decreasing to 75° N.L., where it is at 

 a level with the sea. The snow line in the southern hemi- 

 sphere, whether as influenced by latitude or elevation, is little 

 known ; but in the picture it is regulated so as to harmonise 

 with the line in the northern hemisphere, and with such facts 

 as have been discovered. The sea at both poles is covered 

 with ice; in the southern hemisphere {Jig, 104. h) in a larger, 

 in the northern (Jig. 103. i) in a smaller, proportion. The land, 

 if any exists under this ice, is without organised life, except in 



