506 



POUCHES AND COLUMNS OF RECTUM. 



nucleus-corpuscle. According to Mr. Nasmyth* the deepest lamina 

 of the epithelium appears to consist of nuclei only, in the next the 

 investing vesicle is developed ; the vesicles by degrees enlarge and 

 become flattened, and in the superficial laminae are converted into 

 thin scales. The nuclei, the vesicles, and the scales, are connected 

 together by a glutinous fluid of the consistence of jelly, which con- 



Fig. 15Lt 



tains an abundance of minute opaque granules. The scales of the 

 superficial layer overlap each other by their margins. During the 

 natural functions of the mucous membrane the superficial scales 

 exfoliate continually and give place to the deeper layers. In the 

 stomach and intestines these bodies are pyriform in shape, and have 

 a columnar arrangement, the apices being applied to the papillary 



* Investigations into the structure of the Epithelium, presented to the medical sec- 

 tion of the British Medical Association, in 1839, published in a work entitled "Three 

 Memoirs on the Developement of the Teeth and Epithelium." 1841. 



t A vertical section of the anterior parietes of the anus, with the whole canal dis- 

 played so as to show the relations of the sacculi of the middle region, and their rela- 

 tions to the surrounding parts, their orifices being marked with bristles. A, A. Co- 

 liimns of the rectum, u, B. Rudiments of columns, c. Internal sphincter. F. Ex- 

 ternal sphincter, i. Rudimentary or imperfect sacculi. K, K. Radiated folds of the 

 skin, terminating on the surface of the nates, n. A bristle in one of the sacs. G. 



