PREFACE 



Ix the following pages an attempt is made to out- 

 line some of the more important principles of the 

 science of Biology, and to illustrate in simple terms 

 the inter-relationship of structure and function in 

 living organisms. Since Biology is founded on Physics 

 and Chemistry, an elementary knowledge of these 

 sciences is presupposed, such as may be gained from 

 a study of the volumes of this series dealing with them. 

 Similarly, the present volume is introductory to the 

 Primers of Zoology, Botany, and Physiology, where 

 the fundamental principles here dealt with are treated 

 in greater detail in special relationship to plants and 

 animals respectively. 



It is quite possible that I may have omitted much 

 that another author would have inserted, and enlarged 

 on points which some might consider as out of place 

 in a booklet of this size. Be that as it may, I can only 

 hope that what I have written may prove of interest 

 and service to those whose studies have lain in 

 other departments of knowledge than Biology. 



If errors of fact or exposition are not numerous 

 (it is perhaps too much to hope that they are non- 



