THE TASTE OF ACIDS 461 



SUMMARY 



An attempt has been made to account for the action of acetic 

 and hydrochloric acids upon the sense of taste. It is shown 

 that the stimulus due to these substances probably depends 

 upon their union with diverse constituents of the ceptor surface. 

 It is thus possible to explain, by comparison with the penetration 

 of cells by these acids: how they stimulate at all, why they 

 stimulate to different degrees, and why acetic acid gives a more 

 powerful stimulus than if it acted by dissociation alone. WTiy 

 these acids produce a unitary (sour) taste quahty is a problem 

 of a different order; it is possible that this depends upon the 

 presence of potentially ionizable hydrogen within undissociated 

 acid molecules, though secondary ionization may also play a part. 



agar's island 



BERMUDA. 



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