396 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



teriorly at the commencement of the foregut, yet they may take ori- 

 gin anywhere at the base of the submucosa. 



The outer circular layer is also composed of striated fibres, very 

 coarsely arranged, more so towards the serous coating. The connec- 

 tive tissue sheathing, which separates the longitudinal muscle 

 bundles from each other also widely separates them from the outer 

 .circular muscle coat. 



When the inner surface of the oesophagus ,is folded a small quan- 

 tity of the submucosa enters into the summits of the folds whose cen- 

 tral cavities are filled by the fibres of the muscularis mucosae and by 

 the blood capillaries which pierce the muscularis and delicately branch 

 just under the epithelium. 



The epithelium of the oesophagus is several layered, that is, between 

 the base of the superficial cells are one or two series of cells destined 

 to replace the cast-off superficial ones. The cells constituting the 

 epithelium are long, slender and cylindrical, interspersed among 

 which are a number of beaker cells. The protoplasm of the cylinder 

 cells is granular in the upper half of the cell, to which there is a dis- 

 tinct peripheral wall. The tapering continuations of these can be 

 traced between the younger cylinder cells into the fibrous tissue rest- 

 ing on the muscularis mucosse. Their nuclei are oval and are situ- 

 ated near the basal process of the cell. 



The beaker cells show a size attained nowhere else in the intesti- 

 nal tract. The theca of the cell is much inflated and filled with a 

 mucigenous fluid, in which are scattered faintly refracting bodies. 

 The protoplasm of the cell is found in the basal process surrounding 

 the oval nucleus, which possesses a reticulation, frequently strongly 

 marked. The protoplasm also passes up the sides of the theca for a 

 short distance, in the form of a cap for the mucigenous portion, both 

 portions being quite distinct after maceration. The opening may be 

 as wide as the diameter of the theca, or it may be as narrow as a 

 transverse measurement of the cylinder cell. 



Studied in fresh condition cylinder cells show every stage of degra- 

 dation into beaker cells. The first stage is evinced by the loss of the 

 peripheral wall, followed by a swelling up and transformation of the 

 contents near that end of the cylinder. 



STOMACH. 



At the junction of the oesophagus and stomach the mucous mem- 

 brane becomes more broadly plicated, the folds being irregularly 



