132 THE ADVENTURES OF A GENTLEMAN 



tears have a variety in their passage into the nostril, 

 and there are seven muscles that are employed in 

 the motion of the horse's eye, whereas there are 

 only six in a man ; but a minute anatomical exami- 

 nation would be out of place : the only other point 

 to which I intend to allude is the action of the iris. 

 It is well known that the pupil, as it is called, 

 expands or contracts, as the light is withdrawn or 

 shed upon the eye. This is occasioned by the expan- 

 sion or contraction of the iris ; the former partially 

 closing up the perforation called the pupil, so as 

 to allow less of the dark interior surface of the 

 choroides to be visible through the aperture ; the 

 contraction of the iris, on the other hand, dilating 

 the opening, so as to expose a larger portion of the 

 choroides. Some eminent anatomists have ascer- 

 tained that the iris consists of muscular jBbre, though 

 so delicate as almost to exceed the power of concep- 

 tion to those who are not conversant with the 

 extraordinary powers of nature ; exhibited perhaps 

 to greatest advantage in the minutest of her works. 



If this imperfect sketch of the construction of that 

 wonderful organ, the eye, should only have the effect 

 of tempting my reader to a personal examination of 



