PHYSIOLOGY OF RECONSTITUTION OF PLANARIA LATA. 



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Fig. 22. Head frequencies in relation to length of piece and level of body- 

 in young animals. P. lata: fourths, unbroken line, 150 animals; sixths, 

 dashes, 150 animals. P. diorotocephala: fourths, dotted line, 60 animals; 

 sixths, dots and dashes, 100 animals. The diagrammatic outline below graph 

 indicates levels of section : A—D, large capitals, fourths ; A— F, small capitals, 

 sixths. 



Since the number of animals obtained from eggs was limited, it was not 

 possible to determine whether these differences were characteristic or merely 

 the result of slight differences in experimental conditions. For the present, 

 therefore, it has seemed best to combine these data in tabulation and graphing. 



