CONTENTS xVli 



288. Changes in Genes: Mutations 685 



289. Gene Action 685 



290. Cytoplasmic Inheritance 689 



291. Inheritance of Acquired Characters 690 



292. Human Inheritance 691 



293. Heredity and Environment 692 



294. Medical Genetics 693 



Chapter 34 

 THE CONCEPT OF EVOLUTION 695 



295. The Principle of Organic Evolution 695 



296. Development of Ideas about Evolution 696 



297. Background for The Origin of Species 698 



298. The Theory of Natural Selection 699 



299. Modern Changes in the Theory of Natural 



Selection 700 



300. Genetic Drift 703 



301. Preadaptation 703 



302. Mutations, the Raw Material of Evolution .... 704 



303. Straight-Line Evolution 707 



304. The Origin of Species by Hybridization 709 



305. The Origin of Life 710 



306. Principles of Evolution 713 



Chapter 35 

 THE EVIDENCE FOR EVOLUTION 716 



307. The Fossil Evidence 716 



308. The Geologic Time Table 717 



309. 1 he Geologic Eras 720 



310. The Evidence from Taxonomy 726 



311. The Evidence from Anatomy 727 



312. Evidence from Comparative Physiology and 



Biochemistry 728 



3 1 3. Evidence from Embryology 729 



314. Evidence from Genetics and Cytology 732 



315. Evidence from the Geographic Distribution of 



Organisms 733 



316. The Biogeographical Realms 735 



Chapter 36 

 THE EVOLUTION OF MAN 738 



317. Primate Evolution 738 



318. The Lemurs 738 



