STUDIES ON THE DYNAMICS OF MORPHOGENESIS 

 AND INHERITANCE IN EXPERIMENTAL REPRO- 

 DUCTION 



I. THE AXIAL GEADIENT IN PLAN ARIA DOROTOCEPHALA AS A 

 LIMITING FACTOR IN REGULATION 



. C. M. CHILD 



Hull Zoological Laboratory, Universi'y of Chicago 



FORTY-ONE FIGURES 



CONTENTS 



Introduct ion 265 



Experimental data 273 



1 Material and methods 273 



2 The chief differences in the course and results of regulation of pieces 276 



3 The course and results of regulation in relation to the size of the 



piece and the region of the body represented 284 



4 Tabulation and graphic presentation of data 291 



Discussion 300 



1 The presence of a second zooid 300 



2 The question of 'wholeness' 303 



3 The 'potences' of parts 305 



4 Preliminary analysis of the factor of size of the isolated piece 307 



5 Preliminary analysis of the regional factor in regulation 311 



6 Heredity in the regulation of pieces 315 



Summary 318 



Bibliography 320 



INTRODUCTION 



With the development of the experimental method in zoology 

 an extensive literature on form regulation has arisen : a consider- 

 able portion of this literature, however, either tacitly accepts 

 or positively maintains the view that the phenomena of regula- 

 tion are distinct from those of ' normal ' development and require 



265 



