THE FACTORS OF DISTRIBUTION 



73 



of sunshine, or insolation as it is termed, and its results 

 in evaporation and soil-temperature are also obvious. 

 SURFACE. A factor of minor consequence is the 



Feel 

 16,000 



12,000 



e_85_ ^-8,000 



4,000 





t 



Sea-level -S 



O o5 



111 



"Vgj 



6-2 



character of the surface, mainly as to whether it is even 

 or uneven. Hummocks .or slight irregularities may 

 serve on a small scale as shelter for some low-growing 

 species. 



