G. THE RECTUM, BY E. VERSON. 583 



mucular layer corresponded to it, amounting to nearly double 

 that which this layer ordinarily presents. In a specimen ob- 

 tained from a child I found that in this way the circular mus- 

 cular layer, which at first is 0'21 of a millimeter thick, becomes 

 thickened opposite the fold toO'4 of a millimeter, the longitudinal 

 layer assisting in its formation by the incurvation of some of its 

 fibres. The lowermost fold is situated about 5 6 centimeters 

 above the anus (1 2 centimeters in the newly born child), and 

 occupies the whole of the right wall of the rectum, and from 

 thence may extend to some distance, both anteriorly and pos- 

 teriorly. The one immediately above is situated on the left 

 wall, and the next again on the right, and so on at short inter- 

 vals, alternating from side to side when several valves are 

 present. 



The minute anatomy of the mucous membrane of the rectum 

 presents the same features as those of other parts of the intesti- 

 nal tract. Near the anus, however, the elastic fibres become 

 more abundant, the cellular elements more sparingly distributed, 

 the vessels less numerous, and ultimately it passes into the papil- 

 lated external integument. The muscularis mucosse may be 

 distinctly followed to the point of transition. This layer also, 

 like all the other tunics of the intestine, increases in thickness 

 in the rectum, so that it may equal, or even exceed, 0'2 of a 

 millimeter, whilst the differentiation of its fibres into an external 

 longitudinal and an internal circular layer is lost in the pre- 

 vailing longitudinal direction they assume. Near the anal 

 orifice its fasciculi are closely arranged in the form of cords, 

 which cause the projection of the mucous membrane into seve- 

 ral longitudinal folds (Columnse Morgagni), and then become 

 continuous with delicate tendons which terminate in the skin 

 adjoining the anus. The tendinous mode of termination of 

 the muscularis mucosse is much more easily recognisable in 

 animals than in man, from whom it is difficult to procure suffi- 

 ciently fresh specimens ; in cases where, as in the rat and guinea- 

 pig, the line of transition from the columnar epithelium of 

 the intestine into the tesselated epithelium of the skin occurs 

 abruptly, it exactly coincides with this line. 



The ascending processes which are here also given off by the 

 muscularis mucosse to the interspaces between the Lieber- 



