158 LECTURE IV. 



stices with materials to serve for nourish- 

 ment in the succeeding spring ; and to this 

 Mr. Knight attributes the increased spe- 

 cific gravity of wood felled in the winter 

 season. 



It is in the leaf, however, that the distri- 

 buted fluids of plants seem to undergo their 

 chief elaboration ; for here they are more 

 freely exposed to the influence of light, 

 heat, and air ; much, also, is manifestly 

 thrown off* by perspiration ; and much is 

 probably added, so as to render these juices 

 competent to form, under the agency of 

 the vital energies, that extreme diversity 

 of substances which we meet with in the 

 leaf, the flower, the trunk, and the roots. 



-wt^giSwi*— 



In animals, the matter by which they 

 are nourished, is in general taken into a 

 receptable or stomach, where it undergoes 

 a process called digestion ; and so analo- 

 gous are the functions of life in vegetables 

 and the lower kinds of animals, that Mr. 

 Hunter considered this circumstance as 



