132 SCIENCE PRIMEKS, [§ x. 



you then employ sensory nerves of another kind, the 

 nerves which give us the sense of taste. So also 

 we have nerves of smell, nerves of hearing, and 

 nerves of sight. 



The nerves of touch, where they end, or rather 

 where they begin in the skin, sometimes have and 

 sometimes have not, little peculiar structures attached 

 to them, little organs of touch. So also the nerves 

 of taste, and smell, end or rather begin in a peculiar 

 way. When we come to the nerves of hearing and 

 of seeing, we find these beginning in most elaborate 

 and complicated organs, the ear and the eye. * 



Of all these organs of the senses you will 

 learn more hereafter ; meanwhile, 1 want you to 

 understand that by means of these various sensory 

 nerves, we are, so long as we are alive and awake, 

 receiving impressions from the external world, sensa- 

 tions of touch, sensations of roughness and smooth- 

 ness, of heat and cold, sensations of goo^ and bad 

 odours, sensations of tastes of various kinds, sensa- 

 tions of all manner of sounds, sensations of the 

 colours and forms of things. 



By our skin, by our nose, by our tongue and palate, 

 by our ears, and above all by our eyes, impressions 

 caused by the external world are for ever travelling up 

 sensory nerves to the brain ; thither come also impres- 

 sions from within ourselves, telling us where our limbs 

 are and what our muscles are doing. Within the 

 brain these impressions become sensations. They 

 stir the brain to action ; and the brain, working on 

 them and by them, through ways we know not of, 

 governs the body as a conscious intelligent will. 



