BOOK I. 



ORGANOGRAPHY;" OR STRUCTURAL AND MORPHOLOGICAL 

 BOTANY 



The most superficial examination of any common plant en- 

 ables us to distinguish various parts, such as the root, stem, 

 leaves, &c.; if more minutely examined, it will be found that 

 these parts are not themselves elementary, but that they are 

 also made up of others, in the form of little membranous sacs, 

 and tubes, of different sizes and shapes, combined together 

 in various ways. Before we examine therefore the more evi- 

 dent, or as they are called, compound organs of the plant, it 

 will be necessary for us to explain fully the elementary structures 

 of which they are composed. This division of our subject is 

 termed Vegetable Histology. 



CHAPTER 1. 



ELEMENTARY STRUCTURE OF PLANTS, OR VEGETABLE 

 HISTOLOGY. 



Section 1. Of the Cell as an Individual. 



All plants in their earliest condition are composed of one or more 

 delicate membranous closed sacs, called cells or utricles. All the 

 organs which afterwards make their appearance in the plant arc 

 also made up of these little bodies, variously modified according to 

 circumstances. The simple cell presents itself, therefore, as the 

 first and most important organ of the plant ; that from which 

 all the others are developed ; and, consequently, the only real 

 elementary organ possessed by it. It demands therefore 

 our particular investigation. In treating of it, we shall first 

 describe its form and size; then proceed to investigate the 

 nature of the membrane of which it is composed ; and lastly, its 

 content <i. 



1. Form of the Cell — The cell in its earliest condition con- 

 sists of an exceedingly thin structureless membrane, enclosing 

 various substances. When developed in a space where it is per- 

 fectly free from the pressure of surrounding bodies, and when 

 equally nourished at all parts of its sm-face, it assumes a more 



