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PROFESSOR J. STEPHENSON AND DR BAINI PRASHAD ON 
General Outline of the Structure of the Glands in Helodrilus. 
In segment x tlie oesophagus suddenly widens to form a pair of pouches (oesopha- 
geal pouches) ; the tube also dilates, though less and less in successive segments, for 
a short distance behind this, and is constricted at the situation of the insertion 
of the septa into its walls. 
The following measurements will give an indication of the outline of the tube in this region ; they 
are taken from a young specimen of II. calvjinosus : — 
In segment ix, diameter of oesophagus '22 — '24 mm. 
In segment x, transverse diameter of whole, including the pouches, '61 mm. Yertical height of 
central part of oesophagus '24 mm., of pouches '37 mm. 
At septum 10/11 the tube is '35 mm. high, '28 mm. broad. 
In segment xi, ‘37 mm. high, '4 mm. broad. 
In segment xii, '37 mm. high, '33 mm. broad. 
At septum 12/13, 37 mm. high, *28 mm. broad. 
In segment xiii, "37 mm. high, '35 mm. broad. 
At septum 13/14, '37 mm. high, - 28 mm. broad. 
In segment xiv, ‘35 mm. high, '28 mm. broad. 
A series of transverse sections shows that the pouches in segment x are lateral 
diverticula of the gut, with widely-open mouths, and longitudinally-ridged internal 
lining (fig. ll). On following the series of sections backwards the distal portions 
(the centrally directed ends) of the ridges are seen to fuse with those of their 
neighbours, and in this way, when the fusion of all is complete, a series of longi- 
tudinal tunnels is formed. These extend backwards through segments xi-xiv ; the 
lumina of the tunnels are lined by an epithelium which is continuous at their anterior 
ends with that of the oesophageal pouches, and so with that of the oesophagus. As 
in Eutyphceus, the muscular coat is entirely outside the glands, which are differen- 
tiations of, and included entirely within, the epithelial layer. 
The more detailed description will be most conveniently made by following out 
a series of sections through the successive segments ; for this purpose we select a 
young specimen of Helodrilus caliginosus fixed in formalin. The slight differences 
observed in an adult of the same species, and in H. parvus, will be briefly described 
afterwards. 
The Young Helodrilus caliginosus. 
The Alimentary Canal in segment x. — In the region immediately in front of the 
calciferous glands the epithelium of the oesophagus is thrown into about a dozen 
longitudinal ridges ; there is no layer of rodlets, and no cilia ; the muscular coat is 
thin, 4'5 y in thickness. 
At the level of the anterior part of the oesophageal pouches the epithelium of the 
oesophagus proper (the dorsal and ventral walls) is columnar — the cells extremely 
elongated, with almost rod-like nuclei. The wall of the anterior part of the pouches 
is but little ridged, and the lumen of the pouch is a large open cavity ; the epithelium 
of the proximal part of the pouch, near its opening into the oesophagus, consists of 
