PAET I. 



VEGETABLE ANATOMY, ORGANOGEAPHY, AND 

 PHYSIOLOGY. 



Botany is that brancli of Biological science which comprehends the 

 knowledge of aU that relates to the Vegetable kingdom. It embraces 

 a consideration of the external configuration of plants, their structure, 

 the functions which they perform, the relations which they bear to 

 each other, and the uses to which they are subservient. It takes a 

 comprehensive view of the vegetation with which the earth is clothed 

 at the present day, and of that which covered it at former epochs. 

 It has been' divided into the following departments : — 1. Structural 

 Botany, or Organography/, having reference to the anatomical structure 

 and the forms of the various parts of plants, including vegetable 

 histology, or the microscopical examination of tissues ; and morpho- 

 logy, or the transformations which the organs undergo. 2. Physiological 

 Botany, the consideration of the functions performed by the living 

 plant, or the phenomena of life as exhibited by its various organs 

 during the processes of development, growth, and multiplication. 

 3. Systematical, or Taxological Botany, the arrangement and classifica- 

 tion of plants. 4. Geographical Botany, the distribution of plants 

 in space. 5. Fossil, or Palceontological Botany, the distribution of 

 plants in time, with a description of the form and - structure of the 

 plants found in a fossil state in the various geological formations. 



CHAPTER I. 



ELEMENTAEY OEGANS, OE VEGETABLE TISSUES. 



In their earliest and simplest state plants consist of minute vesicles, 

 each of them bounded by a transparent membrane, which is composed 

 of a substance called Cellulose. This, substance is of general occurrence, 

 and constitutes the basis of vegetable tissues. It "is composed of 

 carbon, hydrogen, and oxygen, and the chemical formula representing 



B 



