l]) half of the cross section of the pollex because the upper cuticle margin was roughly twice as thick as that of the sides or bottom.
b]) could not be computed for all claws for which we obtained safety factors because a few claws broke at the base of the pollex adjacent to the opening where the dactyl inserted, so dimension (f) could not be measured.
4 of standardized pollex length), near the proximal margin of the tanned cuticle (the black ends to the fingers of many brachyuran crab claws), or towards the tip (0.
The fracture plane, however, was not always perpendicular to the upper pollex surface (i.
Under natural conditions, claws may fail mechanically in ways other than the breakage of the pollex that we examined in this study.
Furthermore, by autotransplantation of a pollex
into the eye sockets, a claw with complete proximal segments (ischium, merus, carpus and manus) developed (Kao and Chang, 1997).
Limblike Limb Claw dactyl ipsi 15 6 0 0 dactyl contra 17 8 1 0 pollex ipsi 15 8 2 0 pollex contra 10 3 1 0 dactyl + pollex ipsi 19 13 2 2 dactyl + pollex contra 23 15 1 1 frozen dactyl + pollex ipsi 12 9 0 0 dactyl + pollex + ischium contra 20 15 1 3 ischium + joint ipsi 23 14 1 1 ischium + joint contra 13 10 1 2 Walking leg dactyl + ischium + joint contra 19 12 3 1 Sham operation ipsi 25 18 0 0 Total 211 131 13 10 * Limblike: a structure that resembles a claw or walking leg and in which handedness cannot be recognized; limb: a claw or walking leg in which handedness can be recognized.
Autotransplantation of a combination of distal and proximal claw segments (dactyl + pollex + ischium) into eye sockets regenerated claws or clawlike structures in four cases (26.
The Y-shaped limb [ILLUSTRATION FOR FIGURE 2D OMITTED] resulted from contralateral autotransplantation of dactyl and pollex tissues of the claw.
One mode - regeneration of a complete claw following ecdysis - can occur in autotransplantation of both digits of the claw, the proximal segments of claws (ischium + merus/carpus joint), or a combination of distal and proximal segments of claws (dactyl + pollex + ischium).
The second mode of regeneration occurred in autotransplantation of a combination of distal and proximal claw tissues (dactyl + pollex + ischium) or of both claw digits (dactyl + pollex), but not in autotransplantation of the proximal claw segments (ischium + merus/carpus joint).