48 SECRETION. 



columnar epithelium, is found lining the alimentary canal 

 below the cardiac orifice of the stomach, the biliary pas- 

 sages, the excretory ducts of all the glands, the nasal pas- 

 sages, the upper part of the pharynx, the uterus and Fallo- 

 pian tubes, the bronchi, the Eustachian tubes, and the male 

 urethra. In certain situations this variety of epithelium is 

 provided on its free surface with little hair-like processes 

 called cilia. During life the cilia are in constant motion, 

 producing a current always in the direction of the mucous 

 orifices. Ciliated epithelium is found throughout the nasal 

 passages, commencing about three-quarters of an inch within 

 the nose ; the upper part of the pharynx ; the posterior 

 surface of the soft palate ; the Eustachian tube ; the tym- 

 panic cavity ; the larynx, trachea, and bronchial tubes, un- 

 til they become less than -fa of an inch in diameter ; the 

 neck and body of the uterus ; the Fallopian tubes ; the in- 

 ternal surface of the eyelids, and the ventricles of the brain. 



This variety of mucous membrane is formed of a chorion, 

 a basement-membrane, and epithelium. The chorion is com- 

 posed of inelastic and elastic fibres, with fibro-plastic ele- 

 ments, a few unstriped muscular fibres, amorphous matter, 

 vessels, nerves, and lymphatics. It is less dense and less 

 elastic than the chorion of the first variety, and is generally 

 more closely united to the subjacent tissue. The surface of 

 these membranes is generally smooth, the only exception be- 

 ing the mucous membrane of the pyloric portion of the 

 stomach and the small intestines. 



These membranes are all provided with follicular glands, 

 extending through their entire thickness and terminating in 

 rounded extremities, sometimes single and sometimes double, 

 which rest upon the submucous structure. Many of them 

 are provided also with simple racemose glands, the ducts 

 passing through the membrane, the glandular structure being 

 situated in the submucous areolar tissue. 1 



1 See vol. i., Respiration, p. 361, for a description of the glandular organs 



