XVI 



LIST OF l<'IGC/\/-:s 



83. Conjugation of / \irticella 167 



84. Conjugation of \'octiluca 168 



85. Conjugation of Spirogyra 169 



86. Polar bodies in Jo.\'<>/it'tistfs 174 



87. Genesis of the egg 175 



88. Diagram of formation of polar bodies 177 



89. Polar bodies in Ascaris 178 



90. Genesis of the spermatozoon 180 



91. Diagram of reduction in the male.. . . 181 



92. Spermatogenesis of . Iscaris 184 



93. Tetrads of Gryllotalpa 188 



94. Tetrads and polar bodies in Cyclops.. 189 



95. Diagrams of tetrad-formation in ar- 



thropods 191 



96. Germinal vesicles and tetrads 192 



97. Ovary of Canthocamptus 194 



98. Possible tetrad-formation in the lily. . 197 



99. Conjugation and reduction in Closte- 



rium 198 



zoo. First type of parthenogenetic matura- 

 tion in Artemia 203 



101. Second type of parthenogenetic mat- 



uration in Artemia 204 



102. Modes of tetrad-formation contrasted 206 



103. Abnormalities in the fertilization of 



Ascaris 216 



104. Individuality of chromosomes in As- 



caris 217 



105. Independence of chromosomes in fer- 



tilization of Cyclops 218 



106. Hybrid fertilization of Ascaris 220 



107. Mitosis with intra-nuclear centrosome 



in Ascaris 225 



108. Diagram of different types of centro- 



some and centrosphere 233 



109. Structure of the aster in spermatogo- 



nium of salamander 234 



no. History of chromosomes in the germi- 

 nal vesicle of sharks 245 



in. Nucleated and enucleated fragments 



of Sty lony chia 249 



PAGH 



112. Regeneration in Stentor 250 



113. Nucleated and enucleated fragments 



of Amoeba 25 1 



114. Position of nuclei in plant-cells 253 



115. Ovary of Forficula 25^ 



116. Normal and dwarf larvae of sea- 



urchins 258 



117. Supernumerary centrosome in . \siaris 260 



118. Cleavage of dispermic egg of Toxo- 



pucustes 261 



119. Geometrical relations of cleav.igtv 



planes in plants 266 



120. Cleavage of Synapta 268 



121. Cleavage of Polygordius 269 



122. Cleavage of Nereis 271 



123. Variations in the third cleavage 272 



124. Meroblastic cleavage in the squid. . . . 273 



125. Teloblasts of the earthworm 274 



126. Bilateral cleavage in tunicates 281 



127. Bilateral cleavage in Loligo 282 



128. Eggs of Loligo 283 



129. Eggs and embryos of Corixa 284 



130. Variations in axial relations of Cyclops 286 



131. Half-embryos of the frog 299 



132. Half and whole cleavage in sea-urchins 306 



133. Normal and dwarf gastrulas of Amphi- 



oxus 307 



134. Dwarf and double embryos of Ampki- 



oxus 308 



135. Cleavage of sea-urchin eggs under 



pressure 309 



136. Cleavage of Nereis-eggs under press- 



ure 310 



137. Diagrams of cleavage in annelids and 



polyclades 313 



138. Partial larvae of ctenophores 314 



139. Partial cleavage in Ilyanassa 316 



140. Double embryos of frog 318 



141. Normal and modified larvae of sea- 



urchins 324 



142. Regeneration in ccelenterates 325 



