266 BUREAU OF ANIMAL INDUSTRY. 



between the jreneral sclerotic occupied octween these congested vessels 

 and the anterior rim from which they are absent. Unfortunatel}', the 

 pigment is often so abundant in the anterior part of the sclerotic as to 

 hide this symptom. In internal ophthalmia the opacity of the cornea 

 may be confined to a zone around the outer margin of the cornea, and 

 even this may be a bluish haze rather than a deep fleecy white. In 

 consequence it l)ecomes possible to see the interior of the chamber for 

 the aqueous humor and the condition of the iris and pupil. The 

 aqueous humor is usually turbid, and has numerous yellowish white 

 flakes floating on its substance or deposited in the lower part of the 

 chamber, so as to cut off the view of the lower portion of the iris. 

 The still visible portion of the iris has lost its natural, clear dark 

 luster, which is replaced by a brownish or yellowish sere-leaf color. 

 This is more marked in proportion as the iris is inflamed, and less so 

 as the inflammation is confined to the choroid. The amount of floccu- 

 lent deposit in the chamber of the aqueous humor is also in direct ratio 

 to the inflammation of the iris. Perhaps the most marked feature of 

 internal ophthalmia is the extreme and painful sensitiveness to light. 

 On this account the lids are usually closed, but when opened the pupil 

 is seen to be narrowly closed, even if the animal has been kept in 

 an obscured stall. Exceptions to this are seen when inflammatory 

 effusion has overfilled the globe of the eye, and by pressure on the 

 retina has paralyzed it, or when the exudation into the substance of 

 the retina itself has similarl}- led to its paralysis. Then the pupil 

 may be dilated, and frequently its margin loses its regular ovoid 

 outline and becomes uneven by reason of the adhesions which it has 

 contracted with the capsule of the lens, through its inflammatory 

 exudations. In the case of excessive effusion into the globe of the 

 eye that is found to have become tense and hard so that it can not be 

 indented with the tip of the finger, paralysis of the retina is apt to 

 result. With such paralysis of the retina, vision is heavil}" clouded or 

 entirely lost; hence, in spite of the open pupil, the finger may be 

 approached to the eye without the animal becoming conscious of it 

 until it touches the surface, and if the nose on the" affected side is 

 gently struck and a feint made to repeat the blow the patient makes 

 no effort to evade it. Sometimes the .edges of the contracted pupil 

 become adlierent to each other by an intervening plastic exudation, 

 and the opening becomes virtually abolished. In severe inflamma- 

 tions pus may form in the choroid or iris, and escaping i)ito the cavity 

 of the acpieous humor show as a yellowish white stratum below. In 

 nearly all cases there is resulting exudation into the lens or its capsule, 

 constituting a cloudiness or opacity (cataract), which in severe and 

 old-standing cases appears as a white fleecy mass behind a widely 

 dilated pupil. In the slighter cases cataract is to bo recognized by 

 examination of the eye in a dark chamber, with an oblique side light, 



