416 SPECIAL HISTOLOGY. 



worthy of remark ; and of the bones it need merely be men- 

 tioned, that the thinnest parts of the ethmoid consist only of a 

 fundamental substance and bone fibres, without any Haversian 

 canals. The nasal cartilages are true cartilages, and most nearly 

 approach those of the larynx, except that the contents of the car- 

 tilage-cells are usually very pale, and without fat, the cell walls 

 little thickened, and the matrix finely granular. Beneath the 

 perichondrium there is, also in this situation, a layer of flat- 

 tened cells, which, on the septum attains a thickness of 0024'", 

 whilst in the interior the cells are more rounded, larger, and 

 disposed in rows, in the direction of the thickness of the 

 septum. 



With respect to the coverings of these parts, the integument of 

 the nose may be first noticed : it is characterised by a thin epi- 

 dermis 0*024 — , 032" / thick, a dense cutis of £'" with minute 

 undeveloped papilla of £ — ^'-" and fine hairs, as well as by a 

 close adipose tissue 1'" thick, intimately united with the car- 

 tilage, containing large sebaceous follicles, extending into the 

 latter, and minute sudoriparous glands -^ — jf 1 in diameter. 

 This external integument, with its sebaceous follicles, and with 

 stronger hairs {vibrissa:) also extends a short distance into 

 the nasal fossa, but not quite so far as the point where the 

 cartilaginous portion of the nose terminates, passing impercep- 

 tibly into the mucous membrane of the olfactory organ, by 

 which all the remaining cavities are lined, though it does not 

 everywhere present the same conditions. As was disco- 

 vered by Todd and Bowman, and I can fully confirm, this 

 mucous membrane is subdivided into a ciliated and a non- 

 ciliated portion, the latter being limited to the uppermost parts 

 of the nasal fossa, where the olfactory nerve is distributed, and 

 consequently should perhaps be termed the olfactory mucous 

 membrane in the stricter sense, whilst the other might retain 

 the old name of " Schneiderian membrane." 



Upon first viewing the latter, it will be found that, although 

 the epithelium vibrates throughout, still that its structure is 

 not everywhere the same, and that we may conveniently dis- 

 tinguish in it the thicker glandular mucous membrane of the 

 proper nasal fossa from the thinner membrane of the accessory 

 sinuses, and of the interior of the spongy bones. The epithe- 

 lium, in both situations, is squamose and ciliated, like that of 



