able to manufacture the food materials necessary for the main- 

 tenance of life from the carbon dioxide of the air and water. 

 Animals, being unable to do this, are obliged to maintain them- 

 selves by consuming the food manufactured by plants, and if 

 plants were exterminated all life on the earth would cease. Thus 

 plants are often called the great food-producers and animals 

 the great food-consumers. At the same time it must be noted 

 that a large group of plants known as the Fungi are excep- 

 tional in this respect, for they possess no chlorophyll and like 

 \ animals depend on green plants for their food. 



Sub-divisions 3. Botany may be sub-divided 



of Botany. j n ^ o fa e following divisions : 



I. Vegetable Morphology. 



II. ,, Anatomy. 

 IIT. Physiology. 

 IV. Classification or Systematic Botany. 



V. Vegetable Pathology. 

 VI. Geographical Botany. 



The study of the economic uses of plants and of their pro- 

 ducts is also sometimes treated as a separate branch which is 

 then termed Economic Botany. 



Vegetable Morphology comprises the study of the form of 

 plant bodies and of the several parts of such bodies as visible 

 to the naked eye. 



Vegetable Anatomy comprises the study of the minute struc- 

 ture of plant bodies as seen by the aid of the microscope. 



Vegetable Physiology comprises the study of the plant as a 

 living being. Just as morphology regards each plant body, 

 or part of such body, as a fact, as something which exists and 

 possesses a certain shape and structure, so Physiology regards 

 it as a factor, as something which is capable of action and of 

 performing definite work. While morphology is content with 

 the knowledge of the existence of certain plant structures, 

 Physiology asks what function these structures fulfil and how 

 they do it. Eegarded from a purely morphological stand-point, 

 the various parts of a plant body are called members. When 

 such parts are regarded as performing some particular kind of 

 work, i.e. from the physiological point of view, they are 

 termed organs. The greater the number of organs, each being 

 adapted to the performance of one or more functions, possessed 

 by a plant, the more highly organised is the plant said to be. 



Although Part III of this book is devoted to Physiology, a 



