PERSPIRATION. 65 



will perspire its own weight of water in the 

 course of 24 hours. 



The loss thus occasioned by the leaves is 

 supplied by crude fluid, a large portion of 

 which is water, absorbed by the roots, and con- 

 veyed up the stem with great rapidity. 



The consequence of such copious perspira- 

 tion is the separation and solidification of the 

 carbonised matter that is produced for the pe- 

 culiar secretions of a species. 



For the maintenance of a plant in health, it 

 is indispensable that the supply of fluid by the 

 roots should be continual and uninterrupted. 



If any thing causes perspiration to take place 

 faster than it can be counteracted by the ab- 

 sorption of fluid from the earth, plants will be 

 dried up and perish. 



Such causes are, destruction of spongioles, 

 an insufficient quantity of fluid in the soil, an 

 exposure of the spongioles to occasional dry- 

 ness, and a dry atmosphere. 



The most ready means of counteracting the 

 evil consequences of an imperfect action of the 

 roots is by preventing or diminishing evapora- 

 tion. 



This is to be effected by rendering the atmos- 

 phere extremely humid. 

 6* 



