round the cylinder like a thread round a screw.  If the cylinder is now removed, we shall have a tube like one of the spiral arms.  The two projecting edges are not actually united, and a needle can be pushed in easily between them.  They are indeed in many places a little separated, forming narrow entrances into the tube; but this may be the result of the drying of the specimens.  The lamina of which the tube is formed seems to be a lateral prolongation of the lip of the orifice; and the spiral line between the two projecting edges is continuous with the corner of the orifice.  If a fine bristle is pushed down one of the arms, it passes into the top of the hollow neck.  Whether the arms are open or closed at their extremities could not be determined, as all the specimens were broken; nor does it appear that Dr. Warming ascertained this point.

Fig. 29. (Genlisea ornata.) Utriculiferous leaf; enlarged about three times. l Upper part of lamina of leaf. b Utricle or bladder. n Neck of utricle. o Orifice. a Spirally wound arms, with their ends broken off.

So much for the external structure.  Internally the lower part of the utricle is covered with spherical papillae, formed of four cells (sometimes eight according to Dr. Warming), which evidently answer to the quadrifid processes within the bladders of Utricularia. [page 448] These papillae extend a little way up the dorsal and ventral surfaces of the utricle; and a few, according to Warming, may be found in the upper part.  This upper region is covered by many transverse rows, one above the other, of short, closely approximate hairs, pointing downwards.  These hairs have broad bases, and their tips are formed by a separate cell.  They are absent in the lower part of the utricle where the papillae abound.

Fig. 30. (Genlisea ornata.) Portion of inside of neck leading into the utricle, greatly enlarged, showing the downward pointed bristles, and small quadrifid cells or processes.

The neck is likewise lined throughout its whole length with transverse rows of long, thin, transparent hairs, having broad bulbous (fig. 30) bases, with similarly constructed sharp points.  They arise from little projecting ridges, formed of rectangular epidermic cells.  The hairs vary a little in length, but their points generally extend down to the row next below; so that if the neck is split open and laid flat, the inner surface resembles a paper of pins,—­the hairs representing the pins, and the little transverse ridges representing the folds of paper through which the pins are thrust.  These rows of hairs are indicated in the previous figure (29) by numerous transverse lines crossing the neck.  The inside of the neck is [page 449] also studded with papillae; those in the lower part are spherical and formed of four cells, as in the lower part of the utricle; those in the upper part are formed of two cells, which are much elongated downwards beneath their points of attachment.