TABLE OF CONTENTS 



CHAPTER I 



PAGE 



Introduction 1 



The Cell, 2 ; Cell Division, 13 ; Methods of Repro- 

 duction, 17 ; The Germ Cells, 19 ; The Life Cycles of 

 Animals, 22. 



CHAPTER II 



General Account of the Germ-cell Cycle in Ani- 

 mals 25 



Protozoa, 25 ; Metazoa, 28. 



CHAPTER III 



The Germ-cell Cycle in the P^dogenetic Fly, 



Miastor 51 



CHAPTER IV 



The Segregation of the Germ Cells in Sponges, Cce- 



lenterates, and Vertebrates ... 69 

 1. Porifera, 69. 2. Coelenterata, 80. 3. Verte- 

 brata, 98. 



CHAPTER V 



The Segregation of the Germ Cells in the Arthro- 



PODA 106 



1. The Keimbahn in the Insects, 106 ; Diptera, 107 ; 

 Coleoptera, 109 (In Chrysomelid Beetles, 109 ; Origin 

 of Nurse Cells, 119; Cyst Formation in Testis, 125; 

 Amitosis, 133 ; Differentiation of Nuclei in Egg, 141) ; 

 Hymenoptera, 143. 2. The Keimbahn in the Crusta- 

 cea, 163. 



ix 



