40 ORGANS 01' DIGESTION. 



the external sphincter, and then ascend upwards for an inch or 

 two in contact with the mucous coat, into which they are final- 

 ly inserted by fasciculi which form the base of the columns of 

 the rectum; many of the fibres, however, terminate also between 

 the fasciculi of the circular fibres. This connexion must have 

 obviously much influence in the protrusions of the mucous coat, 

 which sometimes take place. 



The mucous coat of the rectum is thick, red, and fungous, 

 and abounds in mucous lacunae and glands. It is smoothly laid 

 above, but below it is thrown into superficial longitudinal folds 

 called columns. At the lower ends of the wrinkles, between 

 the columns, are small pouches of from two to four lines in 

 depth, the orifices of which point upwards; they are occasional- 

 ly the seat of disease, and .produce, when enlarged, a painful 

 itching. An original observation of Dr. Physick, on the nature 

 of this affection, and the remedy for which consists in slitting 

 them open or removing them, induced me to look for the ordi- 

 nary natural structure, which I have found to be as now de- 

 scribed.* The wrinkling of the anus is from the influence of 

 the external sphincter ani muscle. In some subjects, large 

 cells are formed in the cavity of the rectum by transverse 

 doublings of the mucous coat only, resembling the valvulse con- 

 niventes of the small intestine; this, however, is not the most 

 frequent arrangement, -though deserving of notice. It takes 

 place under the following mechanism. 



About a finger's length from the anus there is a puckering of 

 the gut, or deep wrinkling, such as occurs in the colon, and it 

 arises from a similar cause, that is, an abbreviation of the lon- 

 gitudinal layer of fibres of the gut: this abbreviation is not cir- 

 cular, but occupies the semi-circumference of the gut on one 

 side, and then a little higher up, the semi-circumference of the 

 other side. This shortening of the gut brings the fasciculi of 

 its circular muscular fibres more together, and, therefore, ac- 

 cumulates them into a greater thickness. At a corresponding 



* See an interesting paper on Fistula in ano r by M. Ribes, in Mem. de la So- 

 eiete D'Emulation, vol. 9, 1826; where the influence of this structure is alluded 

 to. It appears that Glisson and Ruysch first described them as valves. Also, 

 an elaborate and excellent article by Dr. Reynell Coates, in the Cyclopaedia of 

 Pract. Med. and Surgery, Philada. 1835, under the term anus. 



