TOUCH. 381 



effects, the skin has been furnished, in various 

 parts of its surface, with a secreting apparatus, 

 which pours out unctuous or mucilaginous fluids : 

 the oily secretions being more particularly em- 

 ployed as a defence against the action of the 

 air, and the mucilaginous fluids as a protection 

 against that of water. 



The conditions on which the perfection of the 

 sense of touch depends are, first, an abundant 

 provision of soft papillae supplied with numerous 

 nerves; secondly, a certain degree of fineness 

 in the cuticle ; thirdly, a soft cushion of cellular 

 substance beneath the skin ; fourthly, a hard 

 resisting basis, such as that which is provided in 

 the nails of the human fingers ; and lastly, it is 

 requisite that the organ be so constructed as to 

 be capable of being readily applied, in a variety 

 of directions, to the unequal surfaces of bodies ; 

 for the closer the contact, the more accurate will 

 be the perceptions conveyed. In forming an 

 estimate of the degree of perfection in which 

 this sense is exercised in any particular animal, 

 we must, accordingly, take into account the 

 mobility, the capability of flexion, and the figure 

 of the parts employed as organs of touch. 



As touch is the most important of all the 

 senses, inasmuch as it is the foundation of all 

 our knowledge of the material world, so its rela- 

 tive degrees of perfection establish marked dif- 

 ferences in the intellectual sagacity of the several 

 tribes, and have a considerable influence on the 



