VEGETABLE PHYSIOLOGY. 



THE term Physiology, signifies a discourse on nature. 

 Vegetable Physiology explains the nature, appearances, and 

 uses, of the internal organs of Plants. 



Plants being limited in their economy to the functions of 

 nutrition and re-production ; and being fixed to the same 

 spot, during their lives, and therefore in nearly a passive con- 

 dition, require for the performance of these functions, me- 

 chanical organs of a very different kind from those which 

 are necessary to carry on the functions of animal life. 



The organs essential to vegetables, are those which re- 

 ceive and elaborate the nutritive fluids which they require ; 

 those which are subservient to re-production, or perfecting 

 the seeds, and those composing the general frame-work, 6r 

 mechanical portion of the Plant, by which the finer organi- 

 zations are supported. 



As Plants are destined to be permanently fixed in their pla- 

 ces of growth, and yet require the action both of air and 

 light, for their perfection, and as their tender organs must also 

 be defended from the action of the elements, so we find these 

 several objects provided for, by three descriptions of parts, 

 all answering different purposes, and yet all combined in the 

 same individuals. 



These parts are first, the Roots by which the Plants are 

 fixed in their places of growth ; second, the Stems, which 

 support, and elevate the limbs and leaves at the proper height 

 from the ground, and third, the Bark or external covering 

 which protects the internal parts, and answers to the skin of 

 animals. 



Solid and Fluid parts. All Plants, however different in 

 their forms or sizes, are composed of fluid and solid parts. 

 The solid parts are supposed to be permanent, the organs 

 which they constitute, when once perfected, being not sub- 

 let to the changes by waste and repair, which animal solids 

 undergo during life. But the fluids of Plants are changea- 



