VI] 



RELATION TO MATTER 



145 



not. If not fed they present us with a strange 

 spectacle (Fig. 15). Without food, they cannot of 



(a) (b) (c) (d) 



Fig. 15. Planaria lugubris. Four stages in the regeneration of a 

 whole from a longitudinal half. The dotted line in (a) marks 

 the line of the cut. The stippled areas represent regenerated 

 tissue. The figures are all drawn to scale. (After Morgan.) 

 (Slightly magnified.) 



course rebuild their missing block of buildings as we 

 should, with new bricks : indeed, as energy has to be 



H. 10 



