INTRODUCTORY CHAPTER 
I. THE SCIENCE OF BOTANY AND 
. ITS SUB-DIVISIONS. 
The Vegetable Kingdom is composed of a vast number 
of plants of different kinds and of various forms, growing 
in greater or less abundance over most of the surface of the 
globe, except where prevented by extreme drought, cold, or 
darkness. The rocks contain great numbers of fossils, 
representing, in a fragmentary way, some of the plants 
which have occupied the earth in former ages. These 
innumerable facts or phenomena, then, are the groundwork 
or material with which the Science of Botany is concerned ; 
it aims at knowing all about these plants, their life, their 
structure, their relations to the physical environment and 
to other forms of life, their functions and uses, their origin, 
migrations, and distribution, and the laws which govern 
all these, the past history of the vegetable kingdom from 
the commencement of life on the earth, and the relationships 
to one another of all plants, living or extinct. 
The earlier students of plants occupied themselves 
mainly with the detailed study of the external form and 
structure of plants, a study which has gradually become 
more and more comparative and now forms the science 
of morphology , and with the investigation of their uses to 
mankind — the science of economic botany . It was soon 
realised that plants show greater or less degrees of mutual 
similarity in structure, and that they can be arranged in 
groups within groups accordingly : attempts at classifying 
w. 
i 
