CONTENTS. 



Page 



INTRODUCTION 3 



HISTORY OF THE EGG FROM FERTILIZATION TO CLEAVAGE. 



A. Formation of the Blastodisc. 



1. The Ripe Egg 11 



2. Surface Views of the Blastodisc .12 



3. Optical Sections of the Blastodisc 12 



4. Marginal and Subgerminal Derivation of the Blastodisc ... 14 



5. Polar Globules . . « 1G 



B. History of the Pronuclei. 



1. Appearance in the Living Egg 18 



2. Views obtained from Mounted Preparations .... .19 



a. Method ... 19 



b. Observations 20 



a. The Spermatic Body, Position of Microptle, etc. . . 20 



/J. The Polar Spindles 22 



y. The Male Pronucleus .... ... 24 



6. The Female Pronucleus ........ 25 



€. Conjugation of the Pronuclei ..... 26 



£. The Movements of the Pronuclei ...... 26 



77. The Role of the Pronuclei 28 



6. Caryological Terminology 30 



C. History of the Cleavage Nucleus. 



1. The Amphiaster 33 



2. The Division of the Nucleus 35 



EXPLANATION OF THE PLATES 37 



