748 PHYSIOLOGY. 



morphia and cocain produce partial loss of the sense of smell 

 (anosmia). 



Certain odors can antagonize another odor when perceived by 

 separate nostrils, so that no odor is perceived, as acetic acid and 

 ammonia. There is also a relationship between smell and the 

 chemico-physical properties of odors; it follows the periodic law of 

 Mendelejeff. 



The Center of Smell lies in the tip of the uncinate gyms upon 

 the inner surface of the cerebral hemisphere. 



Zwaardemaker's Olfactometer. Eubber tubing, two inches in 

 length, is fitted inside a glass tube, which prevents any particles of 

 odor leaving its surface. Another glass tube is closely fitted inside 

 the rubber tube. When the inner glass is drawn out .7 centimeters, 

 then a normal person can perceive the odor of rubber, when 

 air is drawn through the inner graduated glass tube. Hence the 

 inner glass rod was graduated in degrees of .7 centimeters. If a man 

 can only perceive rubber at 1.4 centimeters, he has only half normal 

 olf action; but in certain cases of considerable want of olf action the 

 odor of rubber is not strong enough to be perceived. Here he used 

 a tube of "gutta percha ammoniacum," which is twenty-four times 

 more powerful as a stimulus than india rubber. It was found, in 

 many cases of anosmia, that certain odors might be smelt to a nor- 

 mal extent, whilst others barely stimulated the olfactory organs. 



