STUDIES ON THE DYNAMICS OF MORPHOGENESIS 



AND INHERITANCE IN EXPERIMENTAL 



REPRODUCTION 



IV. CERTAIN DYNAMIC FACTORS IN THE REGULATORY 



MORPHOGENESIS OF PLAN ARIA DOROTOCEPHALA 



IN RELATION TO THE AXIAL GRADIENT 



C. M. CHILD 



From, the Hull Zoological Laboratory, University of Chicago 



FORTY-SIX FIGURES 



I. Introductory 103 



II. Experimental data 104 



A. The axial factor in regulation under constant external conditions. 104 



B. The axial factor in the regulation of pieces under experimental con- 

 ditions 106 



1. Experiments with anesthetics 108 



a. Alcohol , 109 



b. Ether 118 



2. Experiments with potassium cyanide 122 



3. Experiments with temperature 125 



4. Other experimental conditions 132 



C. The axial factor in relation to anterior and posterior zooids 133 



L Cyanide and temperature experiments 136 



2. Some further cyanide experiments: the relation between 



method and results 143 



III. Discussion 148 



IV. Summary 151 



Bibliography 152 



I. INTRODUCTORY 



In the first paper of this series (Child, '11 c) attention was 

 called to the existence of a gradient or gradients of some sort 

 along the chief axis of the body of Planaria dorotocephala, as 

 indicated by the regional differences in the regulation of pieces. 



In the second paper (Child, 'lie) some evidence was presented 

 for the view that the head region is the dominant region in mor- 



103 



