Ill] 



OF REGENERATION 



273 



S-shaped curve of integration and its bell-shaped differential curve, 

 just as we have seen it in simple cases, or simple phases, of 'the 

 growth of a population or an individual. 



If we amputate one limb of a pair in some animal with rapid 

 powers of regeneration, we may compare from time to time the 

 dimensions of the regenerating hmb with those of its uninjured 

 fellow, and so deal with a relative rather than an absolute velocity. 

 The legs of insect-larvae are easily restored, but after pupation no 

 further growth or regeneration takes place. An easy experiment, 

 then, is to remove a limb in larvae of various ages, and to compare 



100 120 



Fig. 86. Regenerative growth in mealworms' legs. 



at leisure in the pupa the dimensions of the new Hmb with the old. 

 The following much-abbreviated table shews the gradual increase 

 of a regenerating limb in a mealworm, up to final equahty with the 

 normal Hmb, the rate varying according to the usual S-shaped 

 curve* (Fig. 86). 



Rate of regeneration in the mealworm (Tenebrio moHtor, larva) 



Days after amputation 

 % ratio of new limb to old 



16 21 25 34 44 58 70 100 121 

 7 11 20 29 42 71 83 91 100 



* From J. Krizenecky, Versuch zur statisch-graphischen Untersuchung . . .der 

 Regenerationsvorgange, Arch. f. Entw. Mech. xxxix, 1914; xlii, 1917. 



