OLFACTION 631 



temperatures. In one of these, a spatula, plunged in water at 48 to 

 55 Fahr. (9 to 12 C), was applied to a denuded surface, and again, a 

 spatula at 113 to 122 Fahr. (45 to 50 C.). When the patient was 

 requested to tell which was the warmer, the answers were as frequently 

 incorrect as they were correct; but the discrimination was easy and 

 certain when the applications were made to the surrounding healthy 

 skin. When applications at a higher temperature were made to the 

 denuded part, the patient suffered only pain. 



Recent experiments have shown that there are distinct areas of the 

 skin which are sensible to heat and others sensible to cold. These are 

 called heat and cold spots. They are irregularly intercommingled 

 with other areas, some of which are sensitive to painful and some to 

 tactile impressions. Figure 155 shows the arrangement of the heat and 

 cold areas. 



The venereal sense is unlike any other sensation and is general as 

 well as referable to the organs of generation. In this connection, how- 

 ever, it is interesting to note that the tactile sensibility of the palmar 

 surface of the third phalanx of the fingers, measured by the esthesiome- 

 ter, compared with the sensibility of the penis, is as 0.802 to 0.034, or 

 between twenty-three and twenty-four times greater. 



OLFACTION 



The nerves directly connected with the senses of olfaction, vision 

 and audition have little or no general sensibility. As regards the 

 olfactory nerves, the parts to which they are distributed are so largely 

 supplied with branches from the fifth, that it is somewhat difficult to 

 determine the fact of their sensibility or insensibility to ordinary impres- 

 sions. These nerves, however, are distributed to the mucous membrane 

 of that portion only of the nasal cavity that is endowed with the special 

 sense of smell. 



Nasal Fosses. The two irregularly-shaped cavities in the middle 

 of the face, opening in front by the anterior nares and connected with 

 the pharynx by the posterior nares, are called the nasal fossae. The 

 membrane lining these cavities usually is called the Schneiderian mucous 

 membrane, and sometimes, the pituitary membrane. This membrane 

 is closely adherent to the fibrous coverings of the bones and car- 

 tilages by which the nasal fossae are bounded, and it is thickest over 

 the turbinated bones. It is continuous with the membrane lining the 

 pharynx, the nasal duct and lachrymal canals, the Eustachian tube, the 

 frontal, ethmoidal and sphenoidal sinuses and the antrum. There are 

 openings leading from the nasal fossae to all these cavities. 



