VETERINARY OPHTHALMOLOGY. 91 



Persistans. During gestation the pupil is closed by a 

 membrane, and occasionally some part or all of it 

 remains. 



Fig. 50. 



Iridectomy.— (Excision of a portion of the iris ; re- 

 moval of the entire iris is iridavulsion.) Iridectomy 



Fig. 51. 



demands a speculum, fixation forceps, an angular or 

 straight keratome, or Grsetfe knife, iris forceps and 



