RETURN OF THE SAP. 31 



tion of Providence, extending over so vast a scale 

 of being, and demonstrating the unity of plan on 

 which the whole system of organized creation has 

 been devised. 



§ 5. Return of the Sup. 



The sap, which, during its ascent from the roots, 

 contains but a small proportion of nutritious par- 

 ticles, diluted with a large quantity of water, after 

 undergoing in the leaves, as in a chemical labora- 

 tory, the double processes of exhalation and aera- 

 tion, has become much more highly charged with 

 nutriment ; and that nutriment has been reduced 

 to those particular forms and states of composition 

 which render it applicable to the growth of the 

 organs, and the other purposes of vegetable life. 

 This fluid, therefore, corresponds to the blood of 

 animals, which, like the elaborated sap, may be 

 regarded as fluid nutriment, perfectly assimilated 

 to that particular kind of organization, with which 

 it is to be afterwards incorporated. From the cir- 

 cumstance of its being sent back from the leaves 

 for distribution to the several organs where its pre- 

 sence is required, it has received the name of the 

 returjiing sap, that it might be distinguished from 

 the crude fluid which arrives at the leaves, and 

 which is termed the ascending sap. 



The returning sap still contains a considerable 

 quantity of water, in its simple liquid form ; which 

 was necessary in order that it might still be the 

 vehicle of various nutritive materials that are dis- 

 solved in it. It appears, however, that a large pro- 



