What is true of the Indian? 875. Is this sense modified by habit? Give instances. How is this sense sometimes impaired? -=-=-=-=-=-=-=-=-=-=-=-= CHAPTER XLIII. SENSE OF SMELL. 876. This sense is located in the air-passages of the _Nose_. To understand the function of smell, the structure of the nose and nasal cavities, with the distribution of the olfactory nerves, must be first examined. ANATOMY OF THE ORGANS OF SMELL. 877. The NOSE is composed of the _Bones_, _Fi´bro-car´tilages_, and _Mu´cous Mem´brane_, together with its integuments. 878. The BONES of the nose are the nasal, and the nasal processes of the upper jaw. 879. The FIBRO-CARTILAGES give form and stability to the framework of the nose, providing at the same time, by their elasticity, against injuries. They are five in number. 880. The MUCOUS MEMBRANE, which lines the interior of the nose, is continuous with the skin externally, and with the lining membrane of the parts of the throat. The entrance of the nostrils is provided with numerous hairs, which serve as guardians to the delicate membrane of the nose. 881. The NASAL FOSSÆ, or nostrils, are two irregular, compressed cavities, extending from the nose to the pharynx. These cavities are bounded superiorly by the sphenoid and ethmoid bones; inferiorly, by the hard palate. In the middle line they are separated from each other by a bony and fibro-cartilaginous septum; upon the outer wall of each fossa, in the dried skull, are three projecting processes, termed spongy bones. In the fresh fossa, these are covered by a mucous membrane. -=-=-=-=-=-=-=-=-=-=-=-= 876. Where is the sense of smell located? 877-884. _Give the anatomy of the organs of smell._ 877. Name the parts that enter into the structure of the nose? 878. What bones form the framework of the nose? 879. What is the use of the cartilages? 880. What relation has the mucous membrane with other membranes of the nose? 881. Describe the nasal cavities. -=-=-=-=-=-=-=-=-=-=-=-= 882. The space that intervenes between the superior and middle spongy bone, is called the _superior me-a´tus_, or channel; the space between the middle and inferior bone, is the _middle meatus_; and that between the inferior bone and the floor of the fossa, is the _inferior meatus_. [Illustration: Fig. 135. A vertical section of the middle part of the nasal cavities. 7, The middle spongy bones. 8, The superior part of the nasal cavities. 10, The inferior spongy bones. 11, The vomer. 12, The upper jaw. 13. The middle channel of the nose. 14, The lower channel of the nose. 17, The palatine process of the upper jaw-bone. 18, The roof of the mouth covered by mucous membrane. 19, A section of this membrane.]