Viii CONTENTS 



VIII. THE INSECTS Il8 



1. Embryonic development Ii8 



2. Experimental analysis of some types of insect development 123 



3. The transformation into the adult 136 



4. The determination of imaginal characters 140 



IX. THE vertebrates: amphibia and birds 145 



I. From the unfertilised egg to the formation of the blastula 



X. the epigenetics of the embryonic axis 173 



1. Amphibia I73 



2. Birds . 181 

 2. Evocation and individuation 188 



4. The physiology of organiser action 193 



5. What occurs during evocation? 206 



6. Regionally specific evocation 215 



7. Competence 218 



XI. embryo formation in other groups of 223 



VERTEBRATES 



1. Cyclostomes and other primitive fish 224 



2. Teleosts 226 



3. Reptiles , 234 



4. Mammals 230 



5. Comparative geography of the presumptive areas 242 



6. Comparative causal embryology of the vertebrates 246 



XII. ORGAN DEVELOPMENT IN VERTEBRATES 25O 



1. The general form of the embryo 250 



2. The development of the head 253 



3. The gut: anterior portion 256 



4. The trunk: ectodermal organs 258 



5. The trunk: endodermal structures 260 



6. T/je (runfe; mesodermal structures 262 



7. T/je faj/ and hind part of the body 263 



8. The kidneys 265 



9. T/ie limbs 270 



