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Fig. 7. Development of mechanical properties in WECB. Capsule maturation is divided
into three distinct phases: (I) pre-pedal manipulation, (II) pedal
manipulation and (III) post-pedal manipulation. Pre-pedal manipulation
consists of formation of the nascent egg capsule in the nidamental gland
including its transport to the pedal gland. Capsules tested in this phase lack
material cohesiveness on a scale detectable by our testing apparatuses. These
capsules are also very soluble. The pedal manipulation phase involves solely
the treatment and manipulation of the capsule while it is in the ventral pedal
gland. Capsules from this phase are beginning to show elasticity, due
presumably to crosslinking. Post-pedal manipulation includes the deposition of
the capsule either on substrate, or to a growing strand. Capsules in this
phase show the fully developed mechanical properties with a Hookean and yield
region. Additional curing probably occurs over a period of time. (Note, force
scales are different in II and III.) Both figures are composed of raw data
directly from the MTS tensometer. Multiple curves represent different
specimens. Thus, the development of final mechanical and chemical properties
is a time-dependent maturation catalyzed by a sclerotizing mechanism applied
in the VPG.
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