Regeneration 175 



regenerating piece of worm. He assumes that through 

 muscular action the liquids of the body are forced to 

 stream toward this end, and that this fact has some con- 

 nection with the formation of a new head. There can 

 be no doubt that the facts here mentioned agree with 

 Bardeen's suggestion. The oblique pieces in Morgan's 

 experiments which at first have the heads and tails 



FIG. 31 / FIG. 32 



outside the line of symmetry of the middle piece, 

 gradually assume a normal position (Figs. 31, 32). 

 The writer is inclined to believe that this is due to 

 mechanical conditions. The head a e c of such an 

 oblique piece is asymmetrical, the one side a e being less 

 stretched than the other e c. The higher tension of the 

 piece e c will have the effect of bringing e nearer c, since 

 we know that acid formation and hence energy pro- 

 duction increases in proportion to surface, i. e., it must 

 be the greater the more it is stretched. The reverse is 

 true for the tail df b, and the effect here will be that/ 



