SEA-FISHERIES LABORATORY, 235 



posterior part of the tube. The anterior part of the 

 oesophagus is non-ciliated, but the portion extending from 

 about the level of the third diaphragm to the stomach is 

 lined by cells which bear short cilia. 



The oesophageal glands or pouches are somewhat 

 flask-shaped and open into the posterior part of the 

 oesophagus by a hollow stalk (fig. 23 and 35). They are 

 usually greenish in colour, due to the contained secretion, 

 but they may also have a pinkish tinge owing to the large 

 amount of blood present in the sinuses in their walls. 

 These blood sinuses are connected with the lateral 

 oesophageal and dorsal vessels. The cavity of each gland 

 is sub-divided by twenty to thirty incomplete partitions, 

 which, in young specimens or in strongly dilated glands, 

 are mere ridges upon the inner wall of the gland, but in 

 old ones they are, as a rule, lamella? projecting well 

 towards the centre of the pouch (fig. 35). Each partition 

 is produced by infolding of .the wall, and is, therefore, 

 covered on each face by the epithelial lining of the gland. 

 These infoldings of the wall enormously increase the 

 secreting surface of the organ. Between these two 

 epithelial layers is a blood sinus which is slightly enlarged 

 near the' free edge of each partition. The pouch is lined 

 by cubical cells among which are numerous gland cells. 

 The secretion of these glands forms a mucous fluid with a 

 neutral re-action. 



The stomach is covered with patches of yellow cells — 

 the chlorogogenous tissue — which in front are arranged in 

 symmetrical oval areas right and left of the dorsal blood- 

 vessel, while more ventrally they are placed in two or 

 three less regular series (fig. 23). They are separated 

 from one another by blood sinuses. About the level of 

 the tenth setae these areas become sub-equal and are 

 arranged in a spiral manner, and behind the level of the 



