8 FRANKLIN PARADISE JOHNSON 



the ano-rectal line. The zone marked off between these two 

 Unes is broken and raised from place to place by the columns of 

 Morgagni, between which are found the intercolumnar pits or 

 depressions ('godets'). The semilunar valves are found at the 

 inferior extremity of this zone. Two types of epithelia are pres- 

 ent, but it is not clear from the descriptions just where these are 

 to be found. In an accompanying figure, the limits of the two 

 epithelia are definitely shown and the following description is 

 based largely upon the figure and its accompanying legend. The 

 first is the prismatic type of epithelium which, like that of the 

 colon, extends from the ano-rectal line to the bottoms of the sinus- 

 like depressions. The second, the stratified squamous type, 

 lines the internal wall of the sinus, that is, the supero-external 

 wall of the valve. Below the sinuous or ''true anal line" is de- 

 scribed a region which is different from the skin proper, but which 

 takes on more and more the structure of the skin when followed 

 caudallj'. 



This region which is 'termed the ''zone cutanee anale lisse, " 

 extends down to where the hairs begin, a distance of 12 to 20 mm. 

 below the sinuous line. It differs from the skin in that its cells are 

 without pigment, only slightly cornified, the dermal papillae are 

 small and few, and sebaceous and sweat glands are lacking. 



Herrmann and Defosses ('80) state that the mucosa of the 

 inferior extremity of the rectum is not directly continuous with 

 the external integument, but that there exists at this level a cir- 

 cular zone, 6 to 12 mm. in height, corresponding to the muscular 

 columns of Morgagni, and which represents a persistent part of 

 the cloaca of the embryo. On the columns the epithelium is 

 stratified polygonal, with superficial plate-like cells, while in the 

 depressions it is of the stratified prismatic type. 



Herrmann ('80) states that the anal mucous membrane is lim- 

 ited by the 'ano-rectale' and 'ano-cutanee' lines. The first he 

 describes the position of definitely enough when he says here end 

 the intestinal glands and the simple columnar epithelium of the 

 colon, but his statement that it is to be found at the level of the 

 upper borders of the anal valves and rectal columns is not clear. 



