oregonensis claws have a much larger area of black cuticle at the pollex tip (G.
The indirect method we used, based on linearly elastic theory applied to cantilevered beams (Young, 1989), assumes (I) that the pollex, or fixed finger, of the claw exhibited a constant cross-section along its length; (II) that the cuticle is isotropic and homogeneous; (III) that shape variation along the length of the pollex, such as caused by teeth, does not create local points of stress concentration; and (IV) that tensile strength was less than compressive strength (i.
The taper of the pollex (violation of assumption I) undoubtedly introduced some error; however, Young (1989, p.
In addition, breaking force exhibited no apparent predictable variation along the length of the pollex, other than to increase towards the tip [ILLUSTRATION FOR FIGURE 2A OMITTED].
Finally, we were confident that the pollex failed in tension on the upper surface (assumption IV) because all but five of 141 claw tips fractured cleanly in one piece, indicating failure in tension of the upper margin, rather than buckling of the lower margin as observed in crab walking legs (Hahn and LaBarbera, 1993).
Pollex safety factors increased with increasing claw size for all six Cancer species, regardless of whether manus length ([ILLUSTRATION FOR FIGURE 4 OMITTED], Table IVa) or claw wet weight (Table IVb) was used as the measure of claw size.
When all six species were analyzed together, lateral cuticle thickness of the pollex (dimensions h and i, [ILLUSTRATION FOR FIGURE 11 OMITTED]) increased [varies]manus [length.
The two claws with host-site handedness resulted from contralateral autotransplantation of a combination of distal and proximal claw tissues (dactyl + pollex + ischium; [ILLUSTRATION FOR FIGURE 2A OMITTED]), or proximal claw tissues (ischium + menus/carpus joint).
The incomplete claw [ILLUSTRATION FOR FIGURE 3B OMITTED] resulted from contralateral autotransplantation of the claw pollex and had donor-tissue handedness.
Claw pollex contra 1 1 1 dactyl + pollex contra 8 4 1 Sham operation contra 3 2 1
Even autotransplantation of a single claw digit (pollex) resulted in regeneration of a claw with complete proximal segments (ischium, merus, carpus, and manus) but with incomplete distal segments (without a dactyl or pollex, [ILLUSTRATION FOR FIGURE 3B OMITTED].
Autotransplantation of a claw pollex into an eye socket regenerated a claw with incomplete distal segments but complete proximal segments.