GENERAL SUMMARY. 309 



CHAPTER III. 



GENERAL SUMMARY OF THE STRUCTURE OF PLANT-. 



1st. A plant is an organized and living being, devoid 

 of voluntary motion, having neither nerves, muscles, 

 nor a central cavity resembling a stomach, and always, 

 or nearly always, attached to the soil from which it 

 draws its nourishment. 



;3d. Plants are either wholly, or in a great measure, 

 composed of membranous Cellules, closed on all sides, 

 more or less united together, and enclosed, at least in 

 their young state, in a membranous cuticle. Those 

 which are entirely thus formed bear the name of 

 Cellular Plants (Book i. Ch. 2 and 16). 



3d. Those which are thus formed in part, and which 

 are called Vascular Plants, present, besides the 

 cellules, cylindrical tubes which are called Vessels ; 

 these are never naked, but always surrounded by 

 cellules (Book i. Ch. o and 16). 



4th. In vascular plants we observe moreover: — 1st, 

 that the cellules and vessels are united in very different 

 degrees, so as frequently to leave between them empty 

 spaces, called Intercellular Passages ; 2d, that 

 besides the purely membranous vessels, there are bodies 

 rolled spirally, and endowed with great elasticity, which 

 are called Tracheae ; «Sd, that their cuticle is pierced 

 (at least, in almost every part exposed to the air) with 



