When the cluster of capsules (the substance of which is tough,
semi-transparent, gelatine, opal-tinted, soon to be sea-stained a
yellowish green) is slowly expelled from the parent's body--I have been
witness to the birth--each contains about one-sixth ounce of vital
element, fluid and glistening. Physical changes in this protoplasm
manifest themselves in the course of a few days. The central portion
becomes a little less fluid, and from an inchoate blur a resemblance to a
diaphanous shell develops and floats, cloud-like, in a perfectly limpid
atmosphere. Gradually it becomes denser though still translucent, as it
seemingly absorbs some of the fluid by which it is surrounded. The model
of the future animal, exact even to the dainty contours and furrows around
that which represents the spire of the ultimate shell, is still without
trace of visible organs. That, however, its substance is highly complex is
obvious, for as imperceptible development progresses the exterior is
transformed into a substance resembling rice tissue-paper--an infinitely
fragile covering--which from day to day insensibly toughens in texture and
becomes separate from the animal. Faint opaque, transverse ribs are at
this stage apparent, though disappearing later on. Opacity is primarily
manifested at the aperture of the infant mollusc where a seeming
resemblance to an operculum forms, possibly for the protection of vital
organs during nascency. This plaque of frail armour is, however, soon
dismantled, and of course much more happens in the never-ceasing process
than is revealed to the uninitiated.

As the calcareous envelope becomes opaque and solid, the animal within
loses its transparent delicacy, and coincidentally the apex of the
capsule opens slightly. In the meantime the fluid contents have
disappeared, as if the animal had resulted from its solidification. The
animal, too, is a very easy fit in its compartment, and incapable, in its
extreme fragility of withstanding the pressure of a finger. Now it begins