INTRODUCTION 
TO 
BOTANY. 
BOOK I. 
organography; or, of the structure of plants, 
CHAPTER I. 
OF THE ELEMENTARY ORGANS. 
If plants are considered with reference to their internal 
organization, they appear at first sight to consist of a vast 
multitude of exceedingly minute cavities, separated by a 
membranous substance ; more exactly examined, it is found 
that these cavities have a variety of different figures, and 
that each is closed up from those that surround it; if the 
inquiry is carried still farther, it will be discovered that the 
partitions between the cavities are all double, and that by 
maceration in water, or by other methods, the cavities with 
their enclosing membrane may be separated from each other 
into distinct bodies. These bodies constitute what is called 
Vegetable Tissue, or Elementary Organs : they are the Simi- 
lary parts of Grew ; the Tissu organique of Mirbel ; and the 
Parties elementaires, or Parties similaires, of De Candolle. 
The chemical basis of the elementary organs has been 
found to be oxygen, hydrogen, and carbon, with occasionally 
a little nitrogen or azote, combined in various proportions : 
their organic basis is membrane and fibre. The latter only 
are here to be considered. 
