LIST OF FIGURES 



XIX 



FIG. 



81. Ovarian eggs of Limulus and Polyzonium .... 



82. Formation of the spermatozoon in Anasa .... 



83. Transformation of the spermatids of the salamander . 



84. Formation of the spermatozoon in Salainandra and Amphiuma 



85. The same in Helix and in elasmobranchs .... 



86. The same in mammals ....... 



87. Formation of spermatozoids in cycads 



88. Formation of spermatozoids in cryptogams .... 



PACE 



159 



162 

 164 



166 



168 



169 



173 

 174 



89. 



90. 

 91. 

 92. 



93- 

 94. 



95- 

 96. 



97- 

 98. 



99- 

 100. 



lOI. 



102. 

 103. 

 104. 

 105. 

 106. 

 107. 

 108. 

 109. 

 no. 

 III. 



112. 



113- 



CHAPTER IV • 



Fertilization oi Physa ,..180 



Fertilization of /4jrari5 183 



Germ-nuclei of Nematodes . . . . . . . . . . .184 



Fertilization of the mouse . 185 



Fertilization of Pterotrachea 1 86 



Entrance and rotation of sperm-head in Toxopneustes , ..... 187 



Conjugation of the germ-nuclei in Toxopneustes ....... 189 



Diagrams of fertilization . . . . . . . . . . .190 



Fertilization oi Nereis . . . . . . 191 



Fertilization of Cyclops 193 



Fertilization and persistence of centrosomes in Thalassema .... 195 



Entrance of spermatozoon into the egg -197 



Pathological polyspermy . . . 199 



Polar rings of Clepsine 201 



Paths of the germ-nuclei in Toxopneustes 203 



Fertilization of Myzostoma 209 



Fertilization of Pilularia . . . . . . . . . . .216 



Penetration of the pollen-tube in angiosperm.s . 217 



Fertilization of the lily 219 



Fertilization in Zamia 220 



Diagram of conjugation in Infusoria . 223 



Conjugation of Paramceciuin 225 



Conjugation of Vorticella ........... 226 



Conjugation of Noctiluca . 227 



Conjugation of Spirogyra ........ o . . 228 



CHAPTER V 



114. Polar bodies in Toxopneustes 



115. Genesis of the egg 



116. Diagram of formation of polar bodies 



117. Polar bodies in /f^frtrw 



118. Genesis of the spermatozoon 



119. Diagram of reduction in the male 



120. Spermatogenesis of ^5(rar?.f 



121. Diagrams illustrating tetrad -formation 



122. Tetrads of Gryllotalpa 



123. Tetrads and polar bodies in Cyclops 



234 

 235 

 237 

 239 

 240 

 242 



244 

 247 



249 

 250 



