

in THE SENSE OF TASTE 139 



requirements of sucking and of liquid alimentation in general. 

 Moreover, the penetration of liquids into the pores of the taste- 

 buds is facilitated in adults by the mechanical compression of the 

 tongue against the teeth and jaws. 



But how are we to explain the different distribution of specific 

 sensibility for the four primitive tastes ? No definite answer to 

 this is possible. Kiesow, however, assuming a hereditary tendency, 

 holds that the taste organs found in the tongue are specially 

 adapted to external stimuli. He notes the tendency to keep 

 substances that have a pleasant taste longer in the mouth than 

 those which give a disagreeable sensation, the latter being either 

 spat out at once or swallowed quickly. Kiesow attributes the 

 small difference in the sensibility to salt of different parts of the 

 tongue in most individuals to the fact that the saliva of the oral 

 cavity, at least of its anterior part, is approximately equally 

 distributed and everywhere has the same content of salt. It 

 should also be noted that Wundt sees a close relation between 

 these facts and certain mimic facial movements. 



III. An exact distinction and classification of the qualitative 

 differences of tastes, i.e. the qualities of the specific gustatory 

 sensations excited by sapid substances in the peripheral organs of 

 taste, is only possible by the sensorial method that is, by sub- 

 jective appreciation of the fundamental or specific differences in 

 the different sensations of taste. As we are almost completely 

 ignorant of the chemical or physical properties which enable 

 certain substances to excite the peripheral organs of taste, we 

 cannot base any classification upon them. 



In daily life we make a distinction between the sapid sub- 

 stances, based on the affective impression they make upon us rather 

 than on the quality of their tastes : thus we discriminate between 

 agreeable, indifferent, insipid, and disagreeable tastes. Agreeable 

 and disagreeable substances excite different expressional move- 

 ments of the facial muscles ; indifferent and insipid substances 

 produce no facial movements, or at most arouse an expression of 

 indifference or slight disgust. These reactions may be considered \ 

 as instinctive reflexes, because they are involuntary; they were ' 

 even noted by Sternberg in an anencephalic foetus. 



By means of these expressional reactions it is possible even in 

 babies of a few months old and in many animals to distinguish 

 clearly between the sensations aroused by different tastes in the 

 mouth. A sweet taste always gives them a pleasurable sensation-, 

 even when it is in excess. Other substances, on the contrary, 

 give a disagreeable sensation in concentrated solutions, or are 

 indifferent if very dilute. In the first case the reaction is a 

 movement of sucking or licking ; in the second there are efforts 

 at repulsion and evidences of displeasure or disgust. 



In adults there is less predilection for sweet things, and a 



