272 
SIDNEY F. HARMER. 
are retracted the hairs radiate towards the centre of the 
vestibular orifice, immediately behind which they form a 
circlet, so that nothing of an irritant nature can pass through 
the aperture without at once coming into contact with one or 
more of the tentacular sense hairs. 
The calyx, like the tentacles, is well supplied with sense hairs, 
which are most numerous in the neighbourhood of its edge ; 
they occur (rarely) on the ventral portions of the stalk, 
although they are absent nearer its attached end. The con- 
nection of the more dorsal sense-cells with the ganglion could 
not be made out, in consequence of the opacity of the stomach. 
On the right side of fig. 1 is represented a nerve passing down 
the stalk, and giving off a branch to a sense-cell. In other 
regions of the body sense-cells are supplied from various parts 
of the nerves ; none were discovered with certainty on any part 
of the inner wall of the vestibule, although the elongated cells 
of the epistome and oral end of the oesophagus have doubtless 
a sensory function, being probably endowed with the faculty 
of taste or smell. 
The most reliable means of noticing the distribution of the 
sense-cells is in silver-nitrate preparations, fig. 3, for instance, 
representing the entire posterior wall of the calyx of L. cras- 
si cauda. In addition to the large epithelial cells may be 
observed very small cells which are provided with sense hairs 
in the living condition. By staining the silver preparations 
with picrocarmine (fig. 7), each of the small areas of fig. 3 
was seen to be provided with a nucleus, the whole structure 
thus forming a small ectoderm cell. 
In picrocarmine-silver-nitrate preparations was further 
observed the direct continuity between the latter and a nerve 
fibril, swelling into a bipolar ganglion-cell, whose deeper process 
passed directly into a nerve (see also figs. 1 and 8). This 
connection of the sense-cell with the central nervous system 
by means of the interposition of a ganglion-cell invariably 
occurs, whether the latter is isolated in the gelatinous tissue of 
the body, or is a constituent of the ganglion at the base of a 
tentacle (fig. 1, tga.). The connection of these cells with the 
