MUCOUS GLANDS. 



379 



are repaired or replaced. Many elements, like the remains of 

 epithelial cells, are found in the secretion; and also round, nu- 

 cleated masses of protoplasm similar to white blood corpuscles, 

 after the imbibition of water. In the abnormal secretion of a 

 mucous surface during inflammation these mucous corpuscles 

 are, as well as the general amount of secretion, enormously in- 

 creased, so that the secretion may become opaque, and may appear 

 to be purulent. 



FIG. 16- r ). 



Section of the Mucous Membrane of upper part of nasal cavity, showing numerous 

 Mucous Glands cut iu various directions. a, Surface epithelium; b, gland saccule; c, 

 connective tissue lined with secreting cells. (Cadiat.) 



The chief object of the secretion seems to be to protect the mu- 

 cous surfaces, which are rich in delicate nerves and vessels, and 

 are subjected to many injurious influences of a chemical or me- 

 chanical nature. It is analogous to the keratin of the epidermis, 

 and may be regarded as an excretion, since it is not absorbed, but 

 is cast out from the mucous passages, and passes from the intes- 

 tinal tract with the faeces, and from the air passages as sputum, 

 etc. 



