542 THE INTESTINAL CANAL, BY E. KLEIN AND E. VERSON. 



In RABBITS the mucous membrane at the passage of the 

 oesophagus into the cardia presents the same features as in man ; 

 but the external muscular coat differs in some respects both 

 from that of man and that of the dog. For the internal longi- 

 tudinal fasciculi, after diminishing in number and size, com- 

 pletely cease at the lower extremity of the oesophagus ; whilst 

 both the middle circular, and the external longitudinal layers, 

 after they have become entirely composed of smooth muscular 

 fibres, and are increased in thickness, pass each in nearly equal 

 strength respectively into the circular and longitudinal layers 

 of the cardia. 



In the TRITON a few acinous glands occur just above the 

 cardia, at the lower extremity of the oesophagus, in the form of 

 a nearly circular zone, and exhibit the same structure as those 

 in the oesophagus of the frog. They pass directly into the 

 tubular peptic glands of the cardia, the excretory ducts be- 

 coming shorter, and their acini diminishing in number and size. 



The smooth muscular fibres first appearing in the form of 

 small fasciculi around the above-mentioned acinous glands, are 

 arranged where the tubular glands are developed, as an inde- 

 pendent muscularis mucosse, situated externally to the tubes ; 

 whilst the fasciculi of the external muscular coat, which in the 

 lower part of the oesophagus are not distinctly separable into 

 two layers, are here grouped into an internal circular and an 

 external longitudinal layer. 



The same changes which occur in the oesophagus of the frog 

 at the point of transition into the cardia are here in every 

 respect repeated. The portion of the mucous membrane situ- 

 ated internally to the acinous glands, between them and the 

 epithelium, diminishes in thickness in proportion to the reduced 

 length of the excretory ducts of the glands. At the same time 

 the glands decrease in size, are arranged in closer proximity to 

 one another, and pass by gradual transition into the peptic 

 glands, which are at first vesicular, but subsequently more 

 elongated and tubular at their fundus. 



The mucous layer consequently suffers a transposition, in a 

 topographical point of view ; for, whilst above it is situated 

 between the epithelium and the glands, below it extends be- 

 tween the glands themselves, whilst it diminishes in thickness 



