450 SCHNEIDERIAN MEMBRANE. 



by very few of the anatomists of the present day. The texture 

 of the membrane appears to be uniform; and on its surface are 

 a great number of follicles of various sizes, from which flows 

 the mucus of the nose. 



These follicles appear like pits, made by pushing a pin ob- 

 liquely into a surface which retains the form of the impression. 

 They can be seen very distinctly with a common magnifying 

 glass when the membrane is immersed in water, both on the 

 septum and on the opposite surface. They are scattered over 

 the membrane without order or regularity, except that in a few 

 places they occur so as to form lines of various lengths, from 

 half an inch to an inch. The largest of them are in the lower 

 parts of the cavities. 



The surface of this membrane when examined with the mi- 

 croscope, is found to be furnished with the ciliary epithelium, 

 consisting of minute projections or columns, thickly set with 

 fine cilia or fringes, which have a peculiar vibratile motion of 

 their own for carrying on fluids, not well understood. 



It may be presumed that the secretion of mucus is effected 

 here by vessels which are mere continuations of arteries spread 

 upon a surface analogous to the exhalents, and not convoluted 

 in circumscribed masses, as in the case of ordinary glands. 



The arteries of this membrane are derived from various 

 sources : the most important of them is the nasal branch of the 

 internal maxillary, which passes into the nose through the 

 spheno-palatine foramen, and is therefore called the Spheno- 

 palatine Artery. It divides into several twigs, which are spent 

 upon the different parts of the surface of the nasal cavities. 

 Two of them are generally found on the septum of the nose : 

 one, which is small, passes forwards near the middle ; the other, 

 which is much larger, is near the lower part of it. 



Two small arteries, called the anterior and posterior eth- 

 moidals, which are branches of the ophthalmic, enter the nose 

 by foramina of .the cribriform plate of the ethmoidal bone. 

 These arteries pass from the orbit to the cavity of the cranium, 

 and then through the cribriform plate to the nose. In addition 

 to these, there are some small arteries derived from the infra- 



