Elementary Anatomy of a Hound 57 



{h) The Choroid Coat. — This coat is interposed 

 between the sclerotic and the retina or inner layer. 



It is composed of several layers of cells, many 

 being pigmented. 



(c) The Retina, or inner layer, is tliii exceedingly 

 delicate structure and the one mainly concerned with 

 the reception of the light and its transmission to 

 the optic nerve. 



This layer is composed of numerous rod- and cone- 

 like cells arranged in a regular manner, but the 

 structure of the retina is too complicated to enter 

 into in a work of this description. In the interior 

 of the eyeball there are two chambers, one in front 

 of the lens and the other behind it. That in front 

 of the lens contains a clear fluid called the aqueous 

 humour, this chamber being known as the anterior 

 one, in contradistinction to that behind — the posterior 

 chamber, which contains the vitreous humour. 



The lens is a bi-convex crystalliile body covered 

 by a clear structure known as the capsule of the lens, 

 and the latter is suspended in position by means of 

 a deHcate ligament. 



In front of the lens hangs the muscular curtain 

 or iris, which has a central slit or opening popularly 

 known as the pupil of the eye. 



The iris is pigmented, and confers the colour upon 

 the eyes, which of course varies according to the 

 variety of dog. The iris is composed of circular 



