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tity of leaves ; which act in a way mnch 

 easier to conceive than define, in attract- 

 ing the sap upwards. We know that 

 through them, a communication is kept 

 with the atmosphere ; probably, they 

 collect a considerable portion of matter 

 from it. In fact, we believe that their as- 

 sistance is absolutely indispri'SJble ; not 

 only to enable the roots to seek what is ne- 

 cessary for themselves, and the other parts 

 of the plant in the earth, but to enable 

 them to make use of it. In theory, 

 we cannot possibly suppose that Nature 

 placed leaves on trees only to amuse 

 us ; — in practice, we find directly the 

 contrary. 



To prove the point, as shortly as pos- 

 sible, we may note, generally, that a tree 

 divested of a considerable portion of 

 its leaves, in the growing season, after- 

 wards vegetates slowly. The case of 

 gooseberries, infested by caterpillars, is 

 directly in point ; for though the fruit 



