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



that of Man, but its external muscular layer is like that of the Dog. 

 The laminated pavement epithelium increases in thickness down- 

 wards. The mucous membrane is generally of looser texture than 

 in Man. When a muscularis mucosae exists, it is composed of an 

 inner portion, which usually forms a delicate plexus, and a much 

 thicker external portion containing longitudinal bundles of fibres, 

 supporting, especially on its outer surface, large vascular trunks. 

 The papillae of the mucous membrane are few in number in the upper 

 part, of unequal size, conical, with a broad base ; but lower down 

 they become more numerous, so that just below the middle they are 

 in close proximity to each other. 



The muscular layer of the mucous membrane is deficient at the 

 commencement of the oesophagus ; but at a somewhat lower plane it 

 makes its appearance in the form of small scattered fasciculi, composed 

 of a few unstriated fibres, running in a longitudinal direction, and 

 separated by layers of mucous tissue of considerable thickness. In 

 the lower fourth it forms a continuous layer about O04 of a millimeter 

 in width, which is traversed by numerous vessels distributed to the 

 papillae. 



I have not been able to demonstrate acinous glands in the oeso- 

 phagus of the Babbit. The external muscular layer, having an 

 average thickness of 0'85 to 0'2 of a millimeter, is composed, like that 

 of the Dog, of spiral fasciculi, which are thus arranged : In the upper- 

 most portion there are two layers, nearly equal in thickness, of which 

 the internal is circular, the external longitudinal in direction. In 

 the second fourth the circular and longitudinal layers run more or 

 less at right angles to their previous course, so that in the third 

 fourth their relative position is entirely changed, and we now find an 

 internal layer, consisting of longitudinal fasciculi, a middle of circular, 

 and an external of longitudinal fasciculi. In the lowermost fourth, 

 although the thickness of these layers differs, their disposition is 

 unaltered. The most internal layer here becomes constantly thinner, 

 whilst the middle and external progressively increase in thickness. 

 The two first maintain the direction they possess above, but the 

 greater number of the fasciculi of the external layer run obliquely. 

 Unstriated muscular fibres first appear in the lower fourth, and in 

 the external muscular layer of longitudinal fibres ; at first, only in the 

 form of small fasciculi, but lower down increasing so remarkably in 

 number and size that they soon outnumber the striated fibres, both 

 in the external longitudinal layer and in the external portion of the 

 middle circular layer. In the lower parts of the inferior fourth the 





