The sense of Taste is closely allied to that of Touch–in fact some authorities have considered Taste as a very highly developed sense of Touch in certain surfaces of the body, the tongue notably.
It will be remembered that the tongue has the finest sense of Touch, and it also has the sense of Taste developed to perfection. In Taste and Touch the object must be brought in direct contact with the organ of sense, which is not the case in Smell, Hearing, or Sight. And, be it remembered, that the latter senses have special nerves, while Taste is compelled to fall back upon the ordinary nerves of Touch.
It is true that Taste is confined to a very small part of the surface of the body, while Touch is general. But this only indicates a special development of the special area. The sense of Taste also depends to a great extent upon the presence of fluids, and only substances that are soluble make their presence known through the organs and sense of Taste.
Physiologists report that the sense of Taste in some persons is so acute that one part of strychnine in one million parts of water has been distinguished. There are certain occupations, such as that of wine-tasters, tea-tasters, etc., the followers of which manifest a degree of fineness of Taste almost incredible.