FORM-REGULATION IN CCELENTERA AND 

 TURBELLARIA 



By C. M. child 



The following is a brief report of the more important results ob- 

 tained during the author's occupancy of the table of the Smithsonian 

 Institution in the Zoological Station at Naples, from July to Decem- 

 ber, 1903. 



Being convinced by study of various fresh-water Turbellaria, and 

 notably of Stenostoma,'^ of the possibility of experimental analysis and 

 control of various factors of form-regulation, my chief purpose in 

 visiting Naples was to obtain further evidence along this line. The 

 forms employed for most of the work were the polyclad turbellaria, 

 Leptoplana tremeUaris and a small species of Cestoplana, which, so 

 far as I could determine, was undescribed, and several species of 

 the sea-anemone, Cerianthus, especially C. solitariiis, this species 

 being the most abundant and best suited in other respects for ex- 

 perimental work. In addition an experimental study of regulation 

 in Tubnlaria was made, primarily for the purpose of reexamining 

 the remarkable regulative phenomena described by other authors. 

 In this work several new results of some importance were obtained. 



I. Leptoplana 



This form, one of the more common polyclads about Naples, was 

 already known to possess a high degree of regenerative power. In 

 one respect the relation of regeneration to the nervous system was 

 conspicuous ; in no case was a piece able to regenerate a head or 

 cephalic ganglia. All portions of the head removed by cuts anterior 

 to the ganglia or through their anterior portion were rapidly re- 

 generated ; if, however, the cut passed just posterior to the ganglia, 

 the anterior regeneration was very slight — only sufficient to heal the 

 wound — and a new head never appeared. Regeneration in the pos- 

 terior direction was not, however, directly influenced by the presence 

 or absence of the cephalic ganglia. Pieces from the anterior parts 

 of the body, but without cephalic ganglia, regenerated at their pos- 

 terior ends pharynx, genital organs, intestine, and all posterior parts 



^ Cf. Studies on Regulation, Roiix's Archiv, i902-'o3. 



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