CONTENTS 



INTRODUCTION 



PAGE 



I. The Cell Theory . 1 



II. The Recapitulation Theory 3 



III. The Physiology of Development 6 



IV. Embryonic Primordia and the Law of Genetic Restric- 



tion 8 



V. General Characters of Germ-cells 9 



The Sperynatozoon 9 



The Ovum 10 



Comparison of the Germ-cells 12 



YI. Polarity and Organization of the Ovum .... 14 



PART I 



THE EARLY DEVELOPMENT TO THE END OF THE 



THIRD DAY 



CHAPTER I. THE EGG . 17 



Chemical Composition of the Hen's Egg 20 



Formation of the Egg 21 



Abnormal Eggs 26 



Ovogenesis . 26 



CHAPTER II. THE DEVELOPMENT PRIOR TO LAYING 32 



I. Maturation 32 



II. Fertilization 35 



HI. Cleavage of the Ovum 38 



The Hen's Egg 39 



The Pigeon's Egg 43 



IV. Origin of the Periblastic Nuclei, Formation of the 



Germ-wall 47 



V. Origin of the Ectoderm and Entoderm 52 



CHAPTER III. OUTLINE OF DEVELOPMENT, ORIENTA- 

 TION, CHRONOLOGY 61 



Orientation 63 



Chronology {Classification of Stages) 64 



Tables of the Development of the Chick 68 



V 



/ 7 ^ ^f 



