CONTENTS 

 XIX. THE DIFFERENTIATING SYSTEM 406 



XX. INDIVIDUATION — THE FORMATION OF PAT- 415 



TERN AND SHAPE 



1. Primary and secondary expressions of pattern 417 



2. The origination of pattern 418 



3. Some actual patterns ■ 



a. Drosophila wing venation 424 



b. The pentadactyl limb 428 



4. Morphogenesis 



a. Movements of isolated cells 433 



b. Movements of tissues : amphibian gastrulation 437 



5. Measurement of the forces and energy involved in morpho- 



genesis 452 



6. Individuation of the central nervous system in Amphibia 455 



BIBLIOGRAPHY " 4^9 



AUTHOR INDEX 497 



SUBJECT INDEX 503 



