XXVI.] THE EYE. 267 



a. The pigment-layer generally adheres rather 

 to the choroid than to the retina. 



b. Apart from the pigment-layer the retina ap- 

 pears like an expansion of the optic nerve. 



c. The retina is firmly attached to the choroid 

 at the ora serrata. 



B. HiSTOLOGy. 



1. Take an eye which has been cut open and then 

 hardened in potassium bicromate 1 p.c. It is 

 best to take the eye of a large animal, e. g. of an 

 ox. Cut out a piece containing the junction of 

 the sclerotic, cornea and iris. Stain, imbed in 

 spermaceti and castor oil (cp. Lesson xx. § 6), 

 and cut sections extending from the outer to 

 the inner surface. Observe 



a. The irregular connective tissue of the sclerotic 

 passing into the lamellae of the cornea. 



6. The membrane of Descemet (cp. § 2, c.) 

 splitting up at the junction of the cornea 

 and sclerotic into fine transparent bundles, 

 some of which curve round towards the iris, 

 the others spreading out fan-like a short 

 distance into the ciliary process and sclerotic. 

 These bundles of fibres form the ligamen- 

 tum pectinatium iridis. 



c. The ciliary muscle ; consisting of bands of 

 unstriped muscle, radiating from the angle 

 of the iris and cornea. (In the eye of man 



