PHYSIOLOGY OF OLFACTION 



71 



stronger in each instance called forth fatigue more 

 quickly than the weaker. 



Some persons are absolutely devoid of true olfaction, 

 a condition which, as already pointed out, is attendant 

 upon certain deficiencies in the essentials of the olfac- 

 tory apparatus and which is designated as anosmia. 



'Olfacties 

 11 



JO ZO 30 40 50 60 TO BO 90 Sec, 



FIG. 16. Curves of olfactory exhaustion produced by the action of benzoin of 9 and 

 of 3.5 olfacties and iby rubber of 14 and of 10 olf acties, acting for different periods. 

 The threshold values in olfacties are marked on the ordinates and the duration of 

 stimulation in seconds on the abscissa;. After Zwaardemaker, 1895, Fig. 22. 



This state may be congenital or acquired and acquired 

 anosmia may be either permanent or temporary. Some 

 forms of anosmia, like color-blindness, are probably in- 

 heritable Glaser (1918). Of considerable interest from 

 a theoretical standpoint are the cases of partial olfac- 

 tory defects. Winkler noted a patient who was quite 

 incapable of smelling benzoin though he easily recognized 

 musk and another who was just the reverse of the first 



