4 INTRODUCTION 



After he has come to know in a general way about the struc- 

 ture and physiology of seed plants, the student may become 

 acquainted with some typical spore plants. This will open up a 

 new world, illustrating some of the most interesting and funda- 

 mental principles of biological science ; for an understanding of 

 the cell theory of organization and development, the nature of 

 sexual processes, and the evolution of the plant kingdom with 

 its remarkable alternation of generations, can only be gained 

 by tracing the chief steps in the processes through the various 

 groups of alga;, fungi, liverworts, mosses, and ferns. 



For users of the book who wish to begin in the autumn with 

 the study of some seed plant as a whole the following scheme 

 is suggested: 



1. Examine a seed plant in flower, to get an idea of its gross 

 anatomy. Then study the development, structure, and modes 

 of dissemination of the fruit, Outline the structure of seeds 

 and follow the germination of some types. Next take up the 

 structure and physiology of the vegetative members of the plant 

 body, root, stem, and leaf. 



2. Cover as much as may be of Part II, working out the 

 story of the evolution of plants. 



3. Devote the remainder of the year to study of floral struc- 

 tures, field work on families of angiosperms, ecological topics, 

 and an outline of economic botany. 



If desired, the course in botany may begin with the simplest 

 spore plants, tracing the evolution of the plant kingdom through 

 a consecutive study of types, as described in Part II, followed 

 by somewhat detailed work on the structure and physiology of 

 seed plants (Part I), and ecology (Part III). 



