G. THE RECTUM, BY E. VERSON. 579 



The submUCOUS tissue is looser in texture, and hence forms 

 numerous folds or rugae in the caecum and colon, which are 

 capable of being obliterated by extension. The submucous tissue 

 stands here also in connection with the mucosa by means of 

 the septa of the fasciculi of the muscularis externa, and also bv 

 the vessels which traverse the muscularis mucosse. 



The muscularis externa, like that of the small intestine, is 

 arranged in two layers, an internal circular and an external 

 longitudinal ; the conjoint thickness of which in the caecum 

 and colon of the child amounts to 0'6 07 of a millimeter. 



The thickness of the longitudinal layer is in inverse propor- 

 tion to that of the circular ; at the longitudinal bands they are 

 both of equal thickness, but in receding from these the circular 

 layer increases as the longitudinal diminishes. 



The solitary follicles, as is generally admitted, possess no 

 lacteals ; but these, on the contrary, as Teichmann* has shown, 

 are displaced by the follicles, so that their arrangement is much 

 disturbed in their vicinity. The plexus surrounding the follicles 

 consists, as shown by His, of wide lymph sinuses, which are 

 lined by a flat epithelium. J. 



The nerves of the large intestine also present the same 

 general relations as those of the small, both in regard to the 

 plexuses they form between the two muscular layers, and to 

 the ganglionic knots or swellings of Auerbach and of Meissner. 

 The latter are usually spheroidal in form, of relatively large 

 size, but containing singularly small cells. 



The cells may be traced in the form of small chains for a 

 short distance in the course of the several nerve trunks. 

 Each nodal point is invested by a layer of connective tissue, in 

 which, besides spheroidal nuclei, fusiform cells with oblong 

 nuclei can be clearly distinguished. 



G. RECTUM. 



The thickness of the intestinal walls constantly augments as 

 the anal orifice is approximated, so that near the middle of the 



* Teichmann, loc. cit. His, Zeitschrift filr wissenschaftliche Zoologie, 

 Bande xi., xii., and xiii. ; Frey, Virchow's ArcJiiv, Band xxxvi. 

 f v. Recklinghausen, Die Lymphgefdsse, etc. Berlin, 1862. 



