ORGANIC AGENCIES. 



119 



tropical regions, because we find there all the regions 

 (Fig. 65). In going up such a mountain, from sea-level, 

 II, we pass through, 1. A region of palms, so called 

 because of the abundance of palms and palm-like forms, 



./ 



PINES 





HARD WOOO TREES 



PALMS AND TREE -FERNS 



FIG. 65. 



such as bananas, tree-ferns, etc. ; 2. A region of hard- 

 wood, or ordinary foliferous trees ; 3. A region in which 

 pines and pine-like trees predominate ; 4. A treeless 

 region, in which are only shrubs, herbs, and grasses ; and 

 5. A plantless region, or region of perpetual snow. 

 These regions, although we have separated them by lines, 

 of course graduate insensibly into each other. The sec- 

 ond region may often be subdivided into a region of 

 evergreens and a region of deciduous hard-woods. 



Botanical Temperature Re- 

 gions in Latitude. Now, since 

 the above regions are determined 

 wholly by temperature, and since 

 a similar decrease of temperature 

 is found in going from the equator 

 to the poles, we ought to expect 

 similar regions in latitude. And 

 such we find. In going from the 

 equator to the poles we find 1. A 

 region of palms, corresponding to 

 tin- tropic zone ; 2. A region of hard-wood trees, corre- 

 sponding to the temperate zone ; 3. A region of pines and 



FIG. 66. 



