2 so 



Anhnal Life and Intelligence. 



continued and healthful fulfilment of the process of 

 life. 



The sense of taste is called into play by certain soluble 

 substances, or liquids, which must come in contact with 

 the specialized nerve-endings. Under normal circum- 

 stances, the sense of taste is closely associated with that 

 of smell, the result of the combination of the two special 

 senses being a flavour. The bouquet of a choice wine, the 

 flavour of a peach, involve both senses ; quinine involves 

 taste alone ; and garlic and vanilla are nearly, if not quite, 

 tasteless, — what we call their taste is in reality their action 

 on the organ of smell. 



It is difficult to classify tastes. Sweet, bitter, salt, 

 alkaline, sour, acid, astringent, acrid, — these are the pro- 

 minent and characteristic varieties. 



This sense is generally localized in or near the mouth ; 

 in us mainly in the tongue. One manner, but not the only 

 manner, in which the nerves in this region terminate is 

 in the minute flask-shaped taste-buds, which have near 

 one end, where they reach the surface, a funnel-shaped 

 opening, the taste-pore. They are made up of elongated 

 cells, some of which near the centre 

 are spindle-shaped, and are called 

 taste-cells. They are found chiefly 

 round the large circumvallate pajDillae ; 

 but in the rabbit and some other 

 animals they are collected in the 

 folds of a little ridged or pleated patch 

 — the papilla foliata — on each side 

 of the tongue near the cheek-teeth. 

 It is probable that the stimulation 

 of the end-organs of taste is effected by the special mode of 

 molecular vibration due to the chemical nature of the 

 sapid substance. Mr. J. B. Haycroft, in a paper read 

 before the Royal Society of Edinburgh,* suggests that " a 

 group of salts of similar chemical properties have their 



* See abstract in Nature, vol. xxxiv. p. 515. 



.^?^?^ 



Fig. 25.— Taste-buds of 

 rabbit. 



i., section across part of the 

 pleated patch (enlarged) ; li., 

 taste-buds further enlarged. 



