VISION*. 227 



taste being detected till, the palate and that part of the tongue 

 are pressed together in swallowing. Perhaps the accurate 

 pressure of the palate is necessary to bring the dissolved 

 sugar into contact with the taste-cones. 



In what is termed flavour, there is something more than 

 mere taste. The texture of the substance tasted is an ele- 

 ment which enters into flavour; for example, the smoothness, 

 roughness, hardness, or softness ; and these are appreciated by 

 the acute common sensation in the tongue and palate. Smell 

 is another element in flavour ; and, besides that, many tastes 

 and smells are so associated, that the smell brings the taste 

 to mind, and certain aromatic tastes even suggest what seem 

 in some way correspondent odours to the imagination. It is a 

 matter of common observation, that interference with smell, 

 as during an attack of catarrh, interferes with the power of 

 distinguishing flavours. 



There is another curious circumstance which points to a 

 connection between taste and smell. In a number of mam- 

 mals there is a sensory organ on each side of the septum of 

 the nose, close to the floor, called the organ of Jacobson. It 

 is a pouch lined with mucous membrane, receiving a twig 

 from the olfactory nerve, and another from the source which 

 supplies common sensation to the nose and palate; and its 

 orifice is pointed downwards, so that in many animals it is 

 most easily entered through a canal in the fore part of the 

 palate. The use of this organ is hard to conceive; but it 

 brings the distribution of the olfactory nerve very close to 

 the organ of taste. 



The back part of the tongue is supplied by the glosso- 

 pharyngeal nerve, but the anterior three-fourths almost 

 entirely by the gustatory branch of the fifth; and it is dim- 

 cult to avoid the conclusion that both nerves are really nerves 

 of taste. 



168. Vision. If by means of the eye we merely had a 

 sensation varying in intensity according to the amount, and 

 in character according to the colours of the light before us, 

 vision would be a sense completely comparable with taste or 

 smell. But to produce the effect of the landscape, there is 

 required, in addition, an exceedingly fine power of localize,' 

 tion of the impressions made by different rays, not indeed a 



