BOOKS AND CURRENT LITERATURE 25 



relation to the general moisture conditions. Higher temperatures are 

 usually coexistent with adverse moisture conditions and therefore fail 

 to produce the acceleration of growth that might be possible with a 

 more abundant soil moisture supply. Evaporation bears an inverse re- 

 lation to growth throughout most of the eight year period, indicating 

 that the high transpiration which it causes in this semi-arid region is 

 deterrent to growth.— Forrest Shreve. 



