PHYSIOLOGY FOR BEGINM.RS 



acting on the nose through the anterior or the posterior 

 nares. This is proved by the fact that if we hold the nose, 

 or if we are suffering from a severe cold which does away 

 for a time with the sense of smell, we "lose our taste," 

 as we say ; then we cannot well distinguish the flavour 

 of an onion from that of an apple. But holding the nose 

 will not do away with a taste proper like that of sugar or 

 of hops. True tastes may be mixed with other sensations 

 in addition to those of smell, such as pungent, smarting, 

 tingling, or similar sensations. Our judgment of the flavour 



of what we eat is 

 formed after taking 

 into account all the 

 sensations which it 

 gives rise to. 



Smell. -- The 

 organ of the sense 

 of smell is the muc- 

 ous membrane lin- 

 ing the upper part 

 of the cavity of the 

 nose. The nostrils 

 or anterior nares 

 lead into the nasal 

 chambers, whi ch are 



FIG. 9o.-The outer wall of the left nasal cavity. separated from each 



I, The olfactory nerve and its branches ; V, branches of other , b V a m edian 

 fifth nerve; Pa, palate; ST, MT, IT, the three partition. Thefloor 

 turbinal bones covered with mucous membrane. of the n.lSal cham- 



bers is formed by the 



hard and soft palate, which separate them from the mouth. Each 

 nasal chamber opens behind by the posterior nares into the upper 

 part of the pharynx. The roof of the chambers in its front part 

 between the eyes is formed by a plate of bone, the cribriform 

 plate, which separates them from the cranial cavity in which 

 the brain lies. Through this plate of bone, which is perforated 

 by numerous holes, the branches of the olfactory nerves stream 

 from a part of the cerebral hemispheres called the olfactory 

 bulb. Into each nasal chamber three delicate scroll-like bones, 

 called the spongy or turbinal bones, project from the side wall. 



