174 



THE ESSENTIALS OF HISTOLOGY. 



From the remainder of the piece of intestine tear off with forceps the fibres 

 of the circular muscular layer on the one side, and the mucous membrane on 

 the other side, so as to leave only the submucous tissue and the muscularis 

 mucosse. This tissue is also to be mounted flat in glycerine : it contains the 

 plexus of Meissiier. 



Sketch a small portion of each plexus under a high power. 



3. Sections of the large intestine, perpendicular to the surface. These will 

 show the general structure and arrangement of the coats. Sketch under a 

 low power. 



4. Sections of the mucous membrane of the large intestine parallel to the 

 surface, and therefore across the glands. Sketch some of the glands and the 

 interglandular tissue under a high power. 



5. The arrangement of the blood-vessels of the large intestine may be 

 .studied in sections of the injected organ. 



THE SMALL INTESTINE. 



The wall of the small intestine consists, like the stomach, of four coats. 

 The serous coat is complete except over part of the duodenum. 



FIG. 203. PLEXUS OF AUERBACH, BETWEEN THE TWO LAYERS OF THE MUSCULAR COAT 



OF THE INTESTINE. (Cadiat.) 



The muscular coat is composed of two layers of muscular tissue, an 

 outer longitudinal and an inner circular. Between them lies a net- 

 work of lymphatic vessels and also the close gangliated plexus of non- 

 medullated nerve-fibres known as the plexus myentericus of Auerbach. 

 The ganglia of this plexus may usually be seen in vertical sections of 



