370 MANUAL OF HISTOLOGY. 



most abundant at the posterior extremity of the inferior tur- 

 binated bones. Some of these vessels are prolonged throughout 

 the continuity of the bone on the lateral as well as the median 

 side, to appear with greater frequency at the anterior extrem- 

 ity, without, however, regaining the number or size which they 

 possessed at their origin. Where they are less numerous the 

 remaining space is almost entirely occupied by ]arge mucous 

 glands. 



In the bony framework of the inferior turbinated bone, large, 

 bright interspaces are seen in the fine trabecular substance, 

 which are filled with fibrous tissue containing pale lymphoid 

 cells. In this fibrous tissue are usually found transverse sec- 

 tions of delicate vessels, the walls of which are apparently 

 composed of fibrous tissue. In order to reach the outer sur- 

 face these vessels either perforate the bone or lie in recesses 

 separated from the soft parts only by the periosteum. In the 

 middle three-fifths of the bone, where the osseous structure 

 contains the largest cavities, we find in the vicinity of the ves- 

 sels large, round, and polygonal, glistening cells, analogous to 

 marrow-cells. A recent author believes most of the above- 

 mentioned vessels to be lymphatics. The arteries of the infe- 

 rior turbinated bone do not number more than three or four, 

 and are derived from the posterior nasal artery. 



The olfactory region is situated in the uppermost portion 

 of the nasal cavity. Its inferior limit in man has not yet been 

 accurately determined. According to the generally received 

 views of Schultze and Ecker, it is probably limited to the roof 

 of the nasal fossae, the superior turbinated bone, and the cor- 

 responding part of the septum. The mucous membrane of this 

 region is of a dull, yellowish brown color, and is perceptibly 

 thicker and softer than that of the respiratory region. This 

 color proceeds from fine pigment-molecules, which are em- 

 bedded partly in the bodies of the cylindrical epithelial cells, 

 and partly in the cells of an especial gland-formation found 

 here. Soon after death, however, it becomes unrecognizable. 

 Under the microscope the olfactory region is seen to be bound- 

 ed by a tolerably well-defined, serrated border, although isl- 

 ands of ciliated epithelium, such as is found in the respira- 

 tory region, are frequently found scattered about in different 

 parts of it. The differences of structure in the olfactory mu- 

 cous membrane depend upon the character of the epithelium, 



