ORGAN OF SMELLING. 393 



suit. For example, at the anterior orifice of the nostril it is 

 insensibly changed into a thin skin, furnished in the male adult 

 with stiff hairs (Vibrissce ;) and in all the sinuses it is more thin 

 and white than elsewhere, being also smooth and shining,, and 

 not presenting clearly the little pits which are so distinct in the 

 nose. The surface which adheres to the sides of the sinuses, 

 is destitute of a fibrous structure, and resembles condensed but 

 very thin cellular membrane, and is so loosely attached that 

 it peels off with a very inconsiderable force. When the mem- 

 brane of the sinuses is inflamed, it then thickens, admits more 

 red blood, and is thus brought to resemble the pituitary else- 

 where. 



It is extremely difficult to assign a proper use to the simises 

 bordering on and entering into the nose; for, according to Des- 

 sault, the sensation of smell does not exist in them. Bichat 

 believed that they, by being filled with air charged with odor- 

 ous particles, were reservoirs of the latter, serving to prolong 

 the sensation of smell, which would have been too fugitive if it 

 had depended only on the passage of air during respiration. 

 Another problem in regard to these cavities, is the manner in 

 which they discharge the mucus which they secrete. Perfect- 

 ly rigid and unyielding, and so situated that the most frequent 

 attitudes of the head would rather serve to retain, than to dis- 

 charge the contents of most, of them by gravitation, we yet 

 seldom see more than their surface smeared with mucus, and 

 accumulations of it are quite uncommon, except in the diseased 

 state. The secretion in them, it is to be observed, is much 

 less abundant than it is in the nose. 



Of the. Nerves of the Pituitary Membrane.* 



The pituitary membrane is furnished with nerves from two 

 sources; from the olfactory, and from the fifth pair. 



The Olfactory Nerve having formed its bulb, which reposes 

 in the ethmoidal fossa, sends off from the under surface of the 

 bulb, the succession of filaments which penetrate to the nose 

 through the cribriform plate of the ethmoidal bone. The lat- 



* Antonii Scarpa, Anatom. Annotationes, Lib. ii. 



