The bladder also is of the nature of membrane, but of membrane
peculiar in kind, for it is extensile. The organ is not common to
all animals, but, while it is found in all the vivipara, the
tortoise is the only oviparous animal that is furnished therewithal.
The bladder, like ordinary membrane, if cut asunder will not grow
together again, unless the section be just at the commencement of
the urethra: except indeed in very rare cases, for instances of
healing have been known to occur. After death, the organ passes no
liquid excretion; but in life, in addition to the normal liquid
excretion, it passes at times dry excretion also, which turns into
stones in the case of sufferers from that malady. Indeed, instances
have been known of concretions in the bladder so shaped as closely
to resemble cockleshells.

Such are the properties, then, of vein, sinew and skin, of fibre
and membrane, of hair, nail, claw and hoof, of horns, of teeth, of
beak, of gristle, of bones, and of parts that are analogous to any
of the parts here enumerated.