Integuments if the nose.--in their general characters these resemble the skin and mucous membrane of other parts : their peculiarities alone therefore need be here described.
The skin of the nose is smooth and fine, its papillse being small and its cuticle very thin. It is soft, also, and pliant, and usually abun dantly furnished with the sebaceous secretion. The hairs growing in it are numerous and ex ceedingly fine, so that many have denied their existence ; the largest and most closely set are at the lower part of the alee. The follicles enclosing them are deep and narrow ; the co nical pulps long and slender. The sebaceous glands are narrow and elongated ; they lie near the sides of the follicles, have very short ducts, and are placed at but a little distance below the surface of the skin. Their secretion is copious, so that alter death a mass of seba ceous tnatter may be squeezed from the orifice of each hair-follicle; and their ducts as well as the follicles themselves are said to be espe cially liable to be infested by the (Icarus jot liculorunt lately discovered by Dr. Simon.* I find none of the simple utricular follicles de scribed by Cloquet and others in the skin of the nose; probably they were empty hair fol licles.
On the upper three-fourths of the nose, the skin moves freely on the subjacent bones and cartilages, a thin layer of pliant cellular and adipose tissue being placed between them. In the lower fourth, and especially about the base of the nose, the skin is thicker and more com pact titan it is above; there is very little fat beneath it, and what there is is arranged in small and discrete granules; and the cutis, muscle, and fibrous membrane are so closely connected that they are moved together as one rnass.
At the nostrils the skin of the nose turns in wards and is continuous with the mucous membrane, which, after lining the nasal fossm and the cavities opening into them, is con tinued into the pharynx through the posterior nares, and into the nasal duct and Eustachian tube. The boundary between the skin and mucous membrane cannot be strictly drawn. It may be fixed, however, at the part just below which those hairs are implanted which con verge from the inner circumference towards the centre of the nostril, so as to entangle any light body floating in the inspired air. These hairs are of the kind named mbrisse. Like the eye lashes they are short, stiff, slightly curved, and pointed at their free extremities; and they are peculiarly well adapted for examining the mi nute structure of hair. In them also, as well as in the eye-lashes, one may best see the mode in which hairs are shed. In all which fall off spontaneously, or which, being about to fall, may be pulled away without pain, the conical cavity at the lower end, into which the vascular pulp fitted, is closed, having gradually con tracted and shifted itself off the pulp as the hair ceased to be nourished and died.
The follicles of these hairs are similar to those of the hairs of the external integument, and each of them is associated with sebaceous glands, which, like those accompanying the hairs about the orifice of the vagina, are more numerous than in parts less exposed to the con tact of fluids. A whorl of four or more small glands is often associated with a single hair follicle ; and when the hairs fall off, and their follicles partially close, the glands open, as if directly, by a common duct upon the surface.
The mucous membrane (Schneiderian or pitu itary membmne) of the nose is far from uni form in its different parts. It is everywhere, and in some parts inseparably, connected with the periosteum or perichondrium which imme diately covers the bones and cartilages, and which is often spoken of as the internal or deep layer of the fibro-mueous membrane ; but, while the latter is in all parts nearly similar, differing only in thickness and degree of vascularity, the mucous membrane itself presents con siderable diversities.
In the antrum and other supplemental cavi ties of the nose the mucous membrane is thin, but little vascular, and of the simplest kind, having neither papillm nor glands embedded in it. On the turbinated bones, the septum, and the floor of the nostrils it is thick, spongy, red; and turgid with blo'od collected in tbe plexus of large vessels in its areolar tissue. These vessels seem to form in some parts a distinct layer between the periosteum and the proper mucous membrane, but they are ex actly analogous to those of the areolar or sub mucous tissue of other compound mucous membranes, in all of which there is a plane of large vessels from which those of smaller size ascend to the appamtus disposed upon the surface. In the Schneiderian membrane the veins of this plexus far exceed the arteries in size, and their close connection with the veins within the skull may be a provision for re lieving the latter when subjected to an undue pressure of blood. The eptstaxis of plethoric persons and of those who read hard probably has its origin in this connection ; for the pres sure of the blood in the congested cerebral vessels being communicated to the walls of these of the mucous membrane, these will burst more readily than those which are on ,r every side supported by scarcely yielding tis sues. The size of thEse veins, too, and the facility with which they permit distension, (almost resembling in this the veins of an erectile tIssue,) account for the rapidity with which the membmne sometimes swells up, so as in a minute or two to obstruct the passage of the nose.