CONTENTS 



Page 

 The time-graded regeneration field in planarians and some of its cyto- 

 physiological implications . . . . . . . . . . . . . . 121 



H. V. Brmdsted 



Discussion on papers by Waddington and Brondsted . . . . . . 139 



Synchronous divisions in mass cultures of the ciliate protozoon Tetrahymena 

 pyriformis, as induced by temperature changes . . . . . . . . 141 



E. ^euthen and 0. Scherbaum 



Discussion . . . . . . . . . . . . . . . . . . 157 



A study of bacterial populations in which nuclear and cellular divisions are 

 induced by means of temperature shifts .. .. .. .. ..159 



0. Maalee and K. G. Lark 



Discussion . . . . . . . . . . . . . . . . . . 169 



Environmental and genetic control of differentiation in Neurospora . . . . 171 



M. Westergaard and H. Hirsch 

 Discussion . . . . . . . . . . . . . . . . . . 183 



The control of cell division .. .. .. .. .. .. ..185 



M. M. Swann 

 Discussion . . . . . . . . . . . . . . . . . . 195 



On suction in Suctoria . . . . . . . . . . . . . . . . 197 



J. A. Kitching 



Discussion . . . . . . . . . . . . • . . . • . 203 



List of Members . . 205 



