IN HYGIENIC PHYSIOLOGY. 205 



the iris, the ciliary processes, and the choroid, are covered with 

 a layer of dark pigment. 



43. What is " the apple of the eye " ? 



The pupil. 



44. UTiatfonn of (/lasses do old people require ? 



(See Question 22.) 



45. Should we ever ivash our ears ivitli cold water ? 



Rarely, if ever, lest we chill this sensitive organ. 



4(>. What is the object of the winding passages in the 



nose ? 



To furnish additional surface on which to expand the olfac- 

 tory nerve. 



47 '. Can a smoker tell in the darJc, whether or not his 

 cigar is lighted ? 



Sight often seems to be essential to perfect what we call a 

 sensation of taste. 



48. Will a nerve re-unite after it has been cut ? 



Nerve-fiber seems to re-unite as readily as muscle-fiber. 



49. Will the sight give us an idea of solidity ? 



(See Physiology, p. 247, note.) 



50. Why can a skillful surgeon determine the condi- 

 tion of the brain and other internal organs by examining 

 the interior of the eye ? 



(See Physiology, p. 248, note.) 



51. Is there any truth in the idea that the image of the 

 murderer can be seen in the eye of the dead victim ? 



When the flame of a taper is held near and a little on one 

 side of a person's eye, any one looking into the eye from a 

 proper point of view will see three images of the flame, two 

 upright and one inverted. One upright figure is reflected from 

 the front of the cornea, which acts as a convex mirror. The. 



