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



of the middle layers are polyhedral, but rather elongated ; whilst those 

 of the deepest layers are spheroidal, but usually somewhat flattened 

 by mutual pressure, and when they surround a papilla, are directed 

 obliquely towards its longitudinal axis. 



The mucous layer succeeding to the epithelium is a thick felt-like 

 structure, composed of decussating fibres of varying size. From the 

 surface of the mucous layer numerous small, conical, vascular papillae 

 project into the epithelium. The glands of the cesophagus are 

 tubular, and are situated in the mucous layer ; they are limited ex- 

 ternally by the muscular layer of the mucosa, and partially project 

 through that layer with their extremities. The fundus of each ex- 

 hibits from five to seven or more hemispherical projections, so that 

 they resemble acinous glands. Their excretory ducts, as well as 

 their pullulations, are bounded by a very thin membrana propria, 

 lined by a delicate narrow columnar epithelium. In hardened prepara- 

 tions the cylinders are usually found empty (cup or goblet cells, 

 Becherzellen), the flattened nucleus alone remaining attached to one 

 side. 



These glands are always isolated, increase in number towards the 

 crop, and are more sparingly distributed and smaller as they recede 

 from this towards the cervical and the thoracic portions of the 



The muscular layer of the mucosa forms a continuous longitudinal 

 layer of smooth fibres, situated external to the mucosa and its glands, 

 and presenting, where it is in contact with the fundus of a gland, a 

 slight projection and attenuation. Here and there small fasciculi are 

 given off, which run for some distance circularly, and then again become 

 longitudinal. The submucous tissue, containing the larger vascular 

 trunks in its meshes, is continuous with the mucosa and the external 

 fibrous layer of the oesophagus. The external muscular layer is 

 exclusively composed of unstriated muscular fibres, grouped into 

 larger or smaller fasciculi to form an internal circular, and an ex- 

 ternal, somewhat thinner, longitudinal layer. Between these two 

 layers is an almost continuous nervous layer, in which are found 

 numerous ganglion cells, either isolated or united into a plexus. 



Towards the crop the mucous layer becomes more attenuated, and 

 the glands fewer in number ; but the circular muscular layer increases 

 in thickness in relation to the longitudinal. In the crop itself the 

 epithelium presents the same characters as in the oesophagus. The 

 mucous layer is here thinner, and there are no glands. 



The external muscular layer is more attenuated than in the oeso- 



