Chapter VII 



THE CELL-THEORY NOT SUFFICH:NT FOR 

 EXPLALXLVG THE ORGANISM 



T N the preceding chapter the cell-theory was shown to 

 A be inadequate as a complete explanation of tlie organism 

 when tested by studies of embryonic development and by 

 experiments on isolated cells and tissues. We now proceed 

 to consider other phases of the theory which still further 

 show its limitations. 



More General Inadequacy of the Cell-Theory 



(a) As Tested hy the Regeneration and Uestitution of 



Mu t 'da ted O rga nis ?n s 



Few topics of research have a more instructive bearing 

 on the hypothetical portion of the cell-doctrine than has 

 that of regeneration, taking the word in its general meaning. 

 Attention may be called first to the far greater inclination 

 of investigators to neglect cells as such when studying the 

 re-development of organisms that have been deprived of 

 some of their parts than when dealing with their development 

 from the germ. 



Such problems as those of cleavage, of molecular be- 

 havior, and of cell-lineage, which stand out so conspicuously 

 in most researches on ordinary embryonic development, par- 

 ticularly those concerning themselves primarily with early 

 stages, are for the most part conspicuous by their absence 

 in studies on the rehabilitation of mutilated organisms. 



Undoubtedly one reason, }3erhaps the chief reason, for 



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