24 OPHTHALMOLOGY FOR VETERINARIANS 



and are commonly called ' 'grape-kernels" and ' 'soot- 

 balls." The pigment of the posterior layer and that 

 in the meshes of the stroma give color to the iris, and 

 the varied colored irides depend upon the amount of 

 pigment deposited in them. A horse with little or no 

 pigment in the iris is called "wall eyed." Albinos are 

 devoid of pigment. The white rabbit is a good example. 

 In such cases a pinkish reflex is seen, derived from the 

 retinal circulation. 



The pupil varies in size and shape in different animals. 

 In fetal life a delicate membrane covers the pupillary 

 space, known as the membrana pupillaris. This disap- 

 pears a few days or weeks before birth, though in some 

 cases portions of it remain in threadhke forms, known as 

 a persistent pupillary membrane, which is often mis- 

 taken for a pathologic condition. 



The ciliary body is closely connected to the sclerotic 

 coat from the ora serrata to a point near the sclero- 

 corneal junction. It is composed of muscular fibers, 

 connective tissue, blood-vessels, and pigment. The body 

 is circular in shape in relation to the sclerocorneal 

 margin. By making a vertical or horizontal section of 

 the globe the muscle can be studied longitudinally. 

 Such a section gives it a triangular appearance. The 

 muscle-fibers are of two kinds — the longitudinal and the 

 circular. The former comprise the greater portion, and 

 lie externally near the scleral tissue, and are called 

 Briicke's portion, after the discoverer. The latter form 



