Table of Contejtts 



Unit 



Problem 5. What Have We Learned about Frodiicing Neiv Types 

 of Animals and Plants? 



Problem 6. To What Exte?n Can Mankind Be biiproved? 



X. THE EARTH AND ITS INHABITANTS HAVE CHANGED 

 THROUGH THE AGES 



Problem i. What Can We Learn from Rocks about the History 



of the Earth? 

 Problem 2. What Can We Learn from Fossils about Prehistoric 



Living Things? 



Problem 3. What PiLZzUng Facts May Be Explained by Onr Theory 

 of the Origin of Neiv Organisms? 



Problem 4. What Theories Have Been Offered to Explain the 

 Origin of Different Kinds of Animals and Plants? 



Problem 5. What Were the Stages of Man's Development 

 on the Earth? 



BIBLIOGRAPHY 



GLOSSARY 



INDEX 



XI 



493 



508 



520 



521 

 533 

 547 



564 



580 



583 

 599 



Hoxv To Use This Book 



1. How this book is organized. Adven- 

 tures ivith Aniinals and Plants is divided 

 into Units, each of which presents a 

 major topic in biology. When you have 

 rinished studying a Unit you will have 

 learned the most important facts pre- 

 sented in that Unit, and should under- 

 stand the important ideas gro^ving out of 

 those facts. To aid you in reaching this 

 understanding, each Unit is divided into 

 two or more Problems. These Problems 

 may be said to be the chapters of the 

 book. Each Problem title poses a ques- 

 tion, the answer to which is to be ob- 

 tained by studying the text that follows. 



When the answers to all the Problem 

 questions contained in a single Unit are 

 understood, you will have all the infor- 

 mation necessary to an understandincr of 

 the statement at the head of that Unit. 



Each Problem is composed of "para- 

 graphs" headed by a title in boldface 

 type. Each of these paragraphs supplies 

 some information necessary for arriving 

 at the answer to the Problem question. 

 A simple, step-by-step study of the para- 

 graphs, as suggested in the following sec- 

 tion, will help to put vou on the road to 

 success in your biology course. 



2, How to learn from this book. There 



