502 THE SOLIDS. 



a remarkable increase in the thickness of this structure, com- 

 pared with the ciliated region below ; so much so, that it 

 forms an opaque soft pulp upon the surface of the membrane, 

 very different from the delicate, very transparent film of the 

 sinuses and lower spongy bones. The epithelium, indeed, 

 here quite alters its character, being no longer ciliated, but 

 composed of an aggregation of superposed nucleated particles, 

 of pretty uniform appearance throughout ; except that in 

 many instances a layer of those lying deepest, or almost 

 deepest, is of a darker colour than the rest, from the brown 

 pigment contained in the cells. These epithelial particles, 

 then, are not ciliated ; and they form a thick, soft, and 

 pulpy stratum, resting on the basement membrane. The 

 deepest layer often adheres after the others are washed away. 

 On looking on the under surface of this epithelium, when it 

 has been detached, we observe projecting tubular fragments 

 similar to the cuticular lining drawn out of the sweat-ducts of 

 the skin, when the cuticle is removed after maceration. In 

 fact, glands apparently identical with the sweat-glands exist 

 in this region in great numbers. They dip down in the re- 

 cesses of the submucous tissue, among the ramifications of 

 the olfactory nerves ; and their orifices are very easily seen, 

 after the general brown coat of epithelium has been detached, 

 lying more or less in vertical rows ; the arrangement is pro- 

 bably determined by the course of those nerves beneath. 

 They become more and more sparing towards the limits of 

 the olfactory region. The epithelium of these glands is 

 bulky, and, like that of the sweat-glands, contains some pig- 

 ment. As the duct approaches the epithelium of the general 

 surface, its wall becomes thinner and more transparent, and, 

 in its subsequent course upwards, it is difficult to be traced, 

 for it does not appear to be spiral, or its particles to differ 

 from those which they traverse. We have sometimes seen 

 rods of epithelium, apparently hollow, left projecting from 

 the basement membrane, after the brown epithelium has been 

 washed away, and these are perhaps portions of the excretory 

 ducts of these glands." 



In the propriety of the discrimination of this region, and 



