The valve is colourless, highly transparent, flexible and elastic. It
is convex in a transverse direction, but has been drawn (fig. 19) in a
flattened state, by which its apparent breadth is increased. It is
formed,
FIG. 20. (Utricularia neglecta.) Longitudinal vertical section through
the ventral portion of a bladder; showing valve and collar. v, valve;
the whole projection above c forms the collar; b, bifid processes; s,
ventral surface of bladder.
according to Cohn, of two layers of small cells, which are continuous
with the two layers of larger cells forming the walls of the bladder,
of which it is evidently a prolongation. Two pairs of transparent
pointed bristles, about as long as the valve itself, arise from near
the free posterior margin (fig. 18), and point obliquely outwards in
the direction of the antenn . There are also on the surface of the
valve numerous glands, as I will call them; for they have the power of
absorption, though I doubt whether they ever secrete. They consist of
three kinds, which [page 401] to a certain extent graduate into one
another. Those situated round the anterior margin of the valve (upper
margin in fig. 19) are very numerous and crowded together; they consist
of an oblong head on a long pedicel. The pedicel itself is formed of an
elongated cell, surmounted by a short one. The glands towards the free
posterior margin are much larger, few in number, and almost spherical,
having short footstalks; the head is formed by the confluence of two
cells, the lower one answering to the short upper cell of the pedicel
of the oblong glands. The glands of the third kind have transversely
elongated heads, and are seated on very short footstalks; so that they
stand parallel and close to the surface of the valve; they may be
called the two-armed glands. The cells forming all these glands contain
a nucleus, and are lined by a thin layer of more or less granular
protoplasm, the primordial utricle of Mohl. They are filled with fluid,
which must hold much matter in solution, judging from the quantity
coagulated after they have been long immersed in alcohol or ether. The
depression in which the valve lies is also lined with innumerable
glands; those at the sides having oblong heads and elongated pedicels,
exactly like the glands on the adjoining parts of the valve.
The collar (called the peristome by Cohn) is evidently formed, like the
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