CHAPTER XXXIT 



Taste and Smell 



Taste. (a) To test the localisation of taste, direct the subject to close his 

 eyes and put out his tongue. This organ is then dried, and different parts 

 are touched with a small brush or a glass rod moistened with the sapid 

 substance in solution. After each observation the mouth must be rinsed 

 with water. The following solutions may be used for testing the four 



qualities of taste, 

 viz. : for bitter, 1 

 per cent, solution 

 of quinine sul- 

 phate ; for siveet, 

 5 per cent, solu- 

 tion of sugar ; for 

 acid, 2 per cent, 

 solution of citric 

 acid ; and for salt, 

 5 per cent, solution 

 of common salt. 

 Notice the time 

 which intervenes 



FIG. 90. Zwaardemakers olfactometer. n, Nose piece; acr, between the appli- 

 screen ; t, porous tube sliding over graduated glass tube. cation of the sapid 



substance and its 



effect. Record your results as regards localisation upon an outline plan 

 of the tongue. 



(6) Chew a leaf of Gymnema sylvestris, or paint with cocaine solution, 

 and determine whether the taste of any of the varieties of sapid 

 substances is affected. 



(c) Test different parts of the tongue by applying closely-set 

 electrodes arranged to conduct a weak faradising current. 



Smell. The sense of smell is tested by Zwaardemaker's olfactometer, 

 which consists of a glass tube with one end adapted to the nostril, 

 while over the other end a tube constructed of, or impregnated with, 

 the odoriferous substance slides, so that a greater or less amount of its 

 inner surface can be exposed to the air which is passing through the 

 glass tube into the nostril (Fig. 90). 



Printed in Great Britain at THE DARIEN PRESS, Edinburgh. 



