136 FOEESX CULTUBE AND 



their stomata, and stands in immediate correlation to 

 the power of absorption of moisture. Besides, if the 

 evaporation of Eucalyptus- trees is so enormous during 

 heat, and if the often horizontal roots of these trees 

 thus render soil around them very dry, in consequence 

 of the copious conveyance of moisture to the air, 

 they simultaneously, by the rapidity of their evapo- 

 ration in converting aqueous to gaseous liquid, or 

 water into vapor, cause a lowering of the temperature 

 most important in our climate during the months of 

 extreme heat, while their capability of absorbiqg 

 moisture during rain or from humid air must be cora- 

 mensurately great. 



It is beyond the scope of this address to dwell fur- 

 ther on facts like these ; but I was anxious to demon- 

 strate by a mere example how much we have yet to ' 

 learn by patient research before we will have recog- 

 nized in all its details the important part which forest 

 vegetation plays in the great economy of nature. 

 Concerning forest culture, I would very briefly allude 

 to an instance showing how, by the teachings of natu- 

 ral science and thoughtful circumspection, the rewards 

 of industrial pursuits may become surprisingly aug- 

 mented. In the uplands of the Madras Presidency, 

 an ingenious method has been adopted in gathering 

 the harvest of Cinchona-bark, in recent very extensive 

 plantations, by removing it in strips without destroy- 

 ing the cambium layer. Then, by applying moss to 

 the denuded part of the stem, not only is the remov- 

 ed portion of the bark renewed within a year, to the 

 thickness of three years' growth, but the protection 

 of the tender bark against the influence of light and 

 air allows nearly all the quinine and Qtlier alkaloidsi 



