SECT. 235.] OLFACTORY MUCOUS MEMBRANE. 6oj 



measuring, in the sinuses, 0'oi8'" to o - 02o'" in thickness, and in 

 the proper cavity of the nose, as much as 0*042 ' in some places. 

 It is composed, in man, of pale, finely granulated cells, of which 

 the outermost ciliated ones measure up to 0'03'" ; in animals, the 

 cilia produce a current from before backwards. Then follows the 

 proper substance of the mucous membrane, containing very few, if 

 any, clastic elements, and chiefly composed of ordinary nuclciferous 

 connective tissue, with numerous glands imbedded in it, in the 

 portion which lines the proper nasal cavity. These glands are the 

 ordinary racemose mucous glands, of various sizes, with gland- 

 vesicles of o - o2 " to o'04"' in diameter ; and they are so thickly 

 disposed in some places, particularly on the borders of the carti- 

 lages of the septum, and on the lower turbinate bones, that the 

 mucous membrane in these spots acquires a thickness of one or 

 even two lines. This thickness, however, is not attributable to 

 the glands alone, but also to the presence of numerous, almost 

 cavernous, plexuses of veins in the interior of the membrane 

 (Kohlrausch, and myself) ; a sort of erectile tissue is thus produced, 

 particularly in the mucous covering of the margin and hinder part 

 of the lower turbinate bone. The glands are almost completely 

 absent from the accessory cavities, and I have hitherto found 

 them only occasionally in the antrum of Highmore ; and here 

 their excretory ducts and acini were sometimes dilated into muci- 

 ferous cysts, which reached up to half a line in diameter. Except 

 in this situation, the mucous membrane of the accessory cavities 

 is extremely delicate, and is not separable from the periosteum as 

 a special layer ; in the nasal cavity itself, it may readily be peeled 

 off, in spite of its intimate connection with the periosteum, espe- 

 cially at those spots where the glands are numerous. In patholo- 

 gical cases, the mucous covering of the sinuses, and of the turbinate 

 bones in part, may exhibit calcareous deposits of various extent, so 

 that the membrane acquires a white colour (myself, and Virchovv, 

 Entw. d. Schadehjr., p. 41). 



The proper olfactory mucous membrane occupies only the upper- 

 most parts of the septum nasi and of the lateral walls of the proper 

 nasal cavities, in the situation of the uppermost turbinate bones. 

 It extends downwards, therefore, from the lamina cribrosa for 

 about three-quarters of an inch to an inch. Even to the naked 

 eye, it is distinguished from the ciliated mucous membrane imme- 

 diately adjoining it by its greater thickness and colour, being 

 sometimes yellowish, as in man, the sheep, and calf; sometimes 

 yellowish-brown, or brown, as in the rabbit and dog ; and on 



