LIST OF FIGURES xxi 



CHAPTER VIII 



FIG. PAGE 



1 68. Geometrical relations of cleavage-planes in plants 363 



169. Cleavage of Synapta 365 



1 70. Cleavage of Polygordius ........... 367 



171. Cleavage of Nereis 369 



172. Variations in the third cleavage , . . . 370 



173. Meroblastic cleavage in the squid 372 



174. Rudimentary cells in Aricia 373 



175. Teloblasts of the earthworm . 374 



176. Contradiction of Hertwig's rule in Ascaris 376 



177. Bilateral cleavage in tunicates 380 



178. Bilateral cleavage in Loligo 381 



1 79- E gg s of Loligo 382 



1 80. Eggs and embryos of Corixa 383 



181. Variations in axial relations of Cyclops 385 



CHAPTER IX 



182. Half-embryos of the frog 400 



183. Half and whole cleavage in sea-urchins 407 



184. Normal and dwarf gastrulas of Amphioxus 408 



185. Dwarf and double embryos of Amphioxus ........ 409 



186. Cleavage of sea-urchin eggs under pressure 411 



187. Cleavage of Nereis-eggs under pressure 412 



188. Diagrams of cleavage in mollusks and polyclades 414 



189. Partial larvae of ctenophores 418 



190. Partial cleavage in Ilyanassa 420 



191. Double embryos of frog 421 



192. Cleavage in Crepidula . . . . . . . . . 424 



193. Normal and modified larvae of sea-urchins . . 428 



194. Regeneration in ccelenterates 429 



