Gradients of normal and regenerative growth in the pistol-crab, alpheus dentipes.

1. During normal growth of the pistol-crab,Alpheus dentipes, the distribution of growth potential along the antero-posterior axis of the body takes the form of a growth gradient with its high point in the chelae-bearing segment. Values of k are presented in the text. 2. During regenerative growth of the thoracic appendages the normal growth gradient is maintained, with slight modification; the relative rate of growth in length of the chelae is reduced. 3. The absolute and relative rate of regeneration of thoracic appendages is exceedingly rapid (see text for values) and varies with body size. Large males used in these experiments regenerate roughly twice the absolute length of appendage regenerated by small males, during the mean day, but form smaller fractions of normal appendage length. 4. Logarithmic plots of carapace length against appendage length at the end of the period of regeneration yield approximations to straight lines in every instance.HUXLEY's idea of growth partition receives support and is shown to apply in regeneration as in normal growth. 5. The partition coefficients for regenerative growth are smaller than those for normal growth, in general. The constant fractional factor kR/kN is considerably less than unity in the male crusher and its propus and it is suggested that small values of this constant are correlated with high normal growth coefficients.