XX LIST OF FIGURES 



FIG. PAGE 



124. Diagrams of tetrad-formation in arthropods 251 



125. Germinal vesicles and tetrads . . . . . . . . . .252 



126. Maturation in Anasa ............ 254 



127. Maturation in Anasa 255 



128. Diagrams of reduction 259 



129. Maturation in Thalassema 260 



130. Maturation in Thalassema and Zirphcea 261 



131. Maturation in Salamandra 262 



132. The maturation-divisions in angiosperms 264 



133. Maturation in Lilium 266 



134. Maturation in Lilium 268 



135. Diagrams of reduction in the flowering plants 270 



136. Ovary of Canthocamptus ........... 273 



137. Polar spindles without centrosomes ......... 276 



138. Polar bodies in Actinophrys 278 



139. Polar bodies in Actinosphcerium 278 



140. Conjugation and reduction in Closterium 279 



141. First type of parthenogenetic maturation in Artemia 282 



142. Second type of parthenogenetic maturation in Artemia 283 



CHAPTER VI 



143. Abnormalities in the fertilization of Ascaris ....... 295 



144. Giant embryo of Ascaris 296 



145. Individuality of chromosomes in Ascaris 297 



146. Independence of chromosomes in fertilization of Cyclops 298 



147. Hybrid fertilization of Ascaris .......... 300 



148. Mitosis with intranuclear centrosome in Ascaris 305 



149. Abnormal mitoses in Hemerocallis . . . 306 



150. Centrosomes in Chatopterus and Cerebratulus 307 



151. Artificially produced asters and centrosomes in echinoderms .... 308 



152. Diagram of different types of centrosome and centrosphere .... 310 



153. Polar mitoses in Diaulula 312 



154. Astral systems in Unto 313 



155. Astral systems in Cerebratulus and Thalassema 320 



156. Structure of the aster in spermatogonium of salamander 326 



CHAPTER VII 



157. History of chromosomes in the germinal vesicle of sharks 339 



158. Nucleated and enucleated fragments of Stylonychia 342 



159. Regeneration in Stentor 343 



1 60. Nucleated and enucleated fragments of A mceba 344 



161. Nucleated and enucleated fragments of plant-protoplasm 345 



162. Position of nuclei in plant-cells 347 



163. Ovary of Forjicula 349 



164. Normal and dwarf larvae of sea-urchins 352 



165. Supernumerary centrosome in Ascaris . . . . . . . 355 



1 66. Cleavage of dispermic egg of Toxopneustes 356 



167. Centrosomes and cilia 357 



