XVI 



LIST OF FIGURES 



83- 

 84. 



85- 

 86. 

 87. 



88. 

 8g. 

 90. 



91- 



92. 



93- 

 94- 

 95- 



96. 



97- 

 98. 

 99. 



102. 

 103. 



104. 



106. 

 107. 



108. 



109. 



no. 



PAGE 



Conjugation of I 'orticella 167 112. 



Conjugation of .\octiliica 168 j 113. 



Conjugation of Spi7-ogyra 169 ! 



Polar bodies in Toxopneustes 174 j 114. 



Genesis of the egg 175 ' 1 15. 



Diagram of formation of polar bodies 177 ' 116. 



Polar bodies in .-{scans 178 i 



Genesis of the spermatozoon 180 j 117. 



Diagram of reduction in the male. .. . 181 ! 118. 



Spermatogenesis of Asca) is 184 ' 



Tetrads of Gryllotalpa 188 I 119. 



Tetrads and polar bodies in Cyclops.. 189 



Diagrams of tetrad-formation in ar- ! 120. 



thropods 191 121. 



Germinal vesicles and tetrads 192 122. 



Ovary of Caiitkocamptiis 194 123. 



Possible tetrad-formation in the lily. . 197 124. 



Conjugation and reduction in Closte- 125. 



rnim 198 126. 



First type of parthenogenetic matura- 127. 



tion in Ariemia 203 128. 



Second type of parthenogenetic mat- 129. 



uration in .Irtemia 204 130. 



Modes of tetrad-formation contrasted 206 131. 



.Abnormalities in the fertilization of 132. 



.hcaris 216 133. 



Individuality of chromosomes in .As- 



caris 217 134. 



Independence of chromosomes in fer- 

 tilization of Cyclops 218 135. 



Hybrid fertilization of .4scaris 220 



Mitosis with intra-nuclear centrosome' 136. 



in .Ascar/s 225 



Diagram of different types of centro- , 137. 



some and centrosphere 233 



Structure of the aster in spermatogo- 138. 



nium of salamander 234 139. 



History of chromosomes in the germi- 140. 



nal vesicle of sharks 245 141. 



Nucleated and enucleated fragments 



of Stylonychia 249 142. 



P.AGE 



Regeneration in Stentor 250 



Nucleated and enucleated fragments 



of Amoeba 25 1 



Position of nuclei in plant-cells 253 



Ovary of Forficula 255 



Normal and dwarf larvae of sea- 

 urchins 258 



Supernumerary centrosome in .Ascaris 260 

 Cleavage of dispermic egg of Toxo- 

 pneustes 261 



Geometrical relations of cleavage- 

 planes in plants 266 



Cleavage of Synapta 268 



Cleavage of Polygordius 269 



Cleavage of Nereis 271 



Variations in the third cleavage 272 



Meroblastic cleavage in the squid. . . . 273 



Teloblasts of the earthworm 274 



Bilateral cleavage in tunicates 281 



Bilateral cleavage in Loligo 282 



Eggs of Loligo 283 



Eggs and embryos of Corixa 284 



Variations in axial relations of Cyclops 286 



Half-embryos of the frog 299 



Half and whole cleavage in sea-urchins 306 

 Normal and dwarf gastrulas of Amptii- 



oxus 307 



Dwarf and double embryos of .Amphi- 



o.vus 308 



Cleavage of sea-urchin eggs under 



pressure 309 



Cleavage of yV^rifw-eggs under press- 

 ure 310 



Diagrams of cleavage in annelids and 



polyclades 313 



Partial larvae of ctenophores 314 



Partial cleavage in Ilyaiiassa 316 



Double embryos of frog 318 



Normal and modified larvse of sea- 

 urchins 324 



Regeneration in coelenterates 325 



