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PROFESSOR J. STEPHENSON AND DR BA INI PRASHA D ON 
pouches (fig. 12) the oesophageal epithelium has been reconstituted as a definite 
layer, independent of the tunnels which have been separated off below it. It shows 
only a slight degree of ridging, and consists of elongated cells, broader at their free 
surface ; their narrower, deeper ends are consequently separated (fig. 13). These 
deeper ends become divided up, and form, or become part of, a spongy reticulum, 
with large free spaces, which intervenes between the regular oesophageal cell-layer 
and the tunnels below. On this oesophageal epithelium rodlets now make their 
appearance ; these constitute a layer of equable thickness, staining only very 
slightly, and are similar to those described in Eutyphosus ; they become more 
distinct in subsequent segments ; they never show any transition to cilia, as far as 
we have observed. The cells have a more deeply staining free border beneath the 
rodlets ; the nucleus appears homogeneous, and not very sharply distinct from the 
cell-body. 
The tunnels have a beautifully regular arrangement (fig. 12), and are in general 
much elongated— four to five times as high as broad — but shorter in the mid-dorsal 
and mid-ventral lines, especially the latter. Occasionally small lamellae arise within 
the tunnels, and these, on being followed back, are seen to unite with one of their 
neighbours, thus splitting into two a previously existing tunnel, and increasing the 
number of tunnels. In this way a considerable increase in the number is to be 
accounted for ; when first established, in segment x, the number was seen to be 
about 28, while in front of septum 11/12 it has risen to between 60 and 70 (69 
lamellae, including one or two incomplete ones) ; this number is maintained 
approximately (64 lamellae in segments xii and xiii) throughout the rest of 
the gland. 
The cells of the tunnels are more or less cubical ; the protoplasm is homogeneous, 
and stains more lightly than that of the cells lining the oesophageal lumen ; the 
nuclei are ovoid ; and there is a very evident basement membrane to the layer. The 
end of the tunnel, which is towards the oesophageal lumen — which may be called its 
roof — is sometimes closed by a flattish cell (fig. 13, y) ; but often the roof is in- 
definite, and the cavity of the tunnel appears to be in communication with the loose 
spongy space which intervenes between the layer of tunnels and the layer of 
oesophageal epithelial cells (as at x). This space is merely crossed by fine trabeculae 
with occasional nuclei. 
In each lamella is a blood sinus — an extension from the general gut sinus which 
lies within the muscular coat external to the tunnels ; the lamellar sinuses, which 
may be potential only, are bounded by the basement membrane of the cell-layers, 
and are dilated at the central ends (towards the oesophageal lumen) (int., fig. 13). 
The basement membrane is always complete round the inner ends of the sinuses, 
though the protoplasmic layer may be thin — merely an extension from the central 
ends of the cell-layers of the lame'llse, or even only a portion of the spongy reticulum 
beneath the epithelial layer of the oesophagus. These internal dilatations are oval 
