Rectal Traclieal Oills. 



221 



of the rectum on oue haiid and by development of muscle layers at the 

 intermediate parts ot the rows on the other hand, the form of a pocket 

 with the opening facing to the central space of the rectum. This opening 

 decreases gradually in dianieter by a nevv formation of epithelium which 

 has buddcd out from the impaired edge of the rectum, and finally has 

 in results total closure. Turning to sections (Textfigurei, \ve find an 

 epithelial tissue tue) which originates at the impaired margin of the rectum. 

 This new tissue increased^ is extended gradually to be joined at last 

 with the corresponding structure of the opposite edge. The cells in this 

 new epithelium arc generally smaller in size, enabling one to distinguish 

 them easily from those of the original epithelium of the rectum, from 

 which they arose. The epithelial cells of the bind intestine are not 

 arranged strictly in single layer, but another series of cells, which is not 



A section of the impaired margine of the rectum iZeiss. obj. D. Oc. 2i. 



bni. basement membrane ; cm. circular, muscles: F. fat cells; g. germinal 



cells of the epithelium; gc. germinal connective tissue cells transformed 



from tp; 1. leucocyte; ne. newly formed epithelium; R. rectum. 



regularly arranged in layer, is found at the bottom of the epithelium : these 

 cells of this series contain protoplasm of fine granulär appearance and 

 stain rather intensively with the anilin color. They are supposed to be 

 the germinal cells which compensated in the course of development, 

 the decayed cells and probably the cells of newly formed epithelium also 

 originate in this germinal cells. 



In connexion with the new formation of epithelium, takes place 

 new formation of the connective tissue which support the epithelium from 

 beneath. The basement membrane passes over into the fibrous substance, 

 the tunica proparia under the rectal epithelium (tp). There is no reason 

 to separate the basement membrane of the branchial epithelium from the 

 tunica propria in the other part of the rectum, since both are the same 

 in nature and origin but the tunica propria in this case not only contains 

 cells arranged in a few indistinct layers but also shows an irregulär fibrous 

 appearance, and serves to connect the epithelium with the underlying 

 muscles. Besidcs these structures the free cells are scattered about the 



