814 DIRECTIONS FOE LABORATORY WORK 



stituent elements, and note its relationship to adjacent structures. 

 Sketch (379). Function of ligamentum pectinatum and the included 

 spaces of Fontana? 



(3) Sketch h.p. (380) the cornea. Identify its five layers. Inner- 

 vation of the corneal conjunctiva? Function of the membrane of Des 

 cemet? Changes in cornea after death or fixation? 



(4) Sketch h.p. (381) the sclera. Location and character of the 

 lamina fusca? 



(5) Sketch h.p. (382) the tunica choroidea. Note the several lam- 

 inae: suprachoroidea, vasculosa, tapetum fibrosum (cellulosum), chorio- 

 capillaris, and lamina basalis (vitrea). Function of the choroid? 



(6) Sketch h.p. (383) the equatorial margin of the crystalline lens, 

 including the zonula ciliaris of Zinn (suspensory ligament) with its 

 spacia zonularis (canals of Petit). Note the lens capsule, lenticular 

 epithelium, and the substantia lentis composed of nucleated lens fibers, 

 with serrated margins. 



(7) Sketch h.p. (384) a segment of the iris. Note: a, its external 

 layer of mesenchymal epithelium ('endothelium') ; b, its fibrous stroma, 

 with its pigmented cells; c, the internal epithelial layer (pars iridica 

 retina?); d, the stromal recesses; e, the dilator and sphincter muscles; 

 and f, the circuli major and minor. Origin and function of the iridal 

 muscles? Relation of pigmented stroma to 'color of eye'? Effect of 

 certain drugs upon the size of the pupil? 



(8) Sketch h.p. (385) the pars optica retinae, or the retina proper, 

 at a point about midway between the macula lutea and the ora serrata. 

 Relation to pars ciliaris retina? and the pars iridica retina?? Identify 

 the eleven different layers. Compare this portion of the retina with that 

 near the fovea centralis and that near the ora serrata. Probable function 

 of: a, the pigment (fuscin) of the pigmented layer; b, the visual purple 

 (rhodopsin) of the rod visual cells; and c, the myoid element of the 

 rods and cones ? Explain the inversion of the retina. Explain coloboma 

 and scotoma. 



(9) In a Golgi preparation of the retina identify the different neu- 

 rons of the several layers and determine their interrelations (synapses). 

 Construct a diagram (386) showing the interrelationships of the ele- 

 ments of the different layers, including the neuroglia supporting cells of 

 Miiller. 



(10) (a) Study an injected specimen of cat's eye. Note the dis- 

 tribution of the branches of the central artery of the retina, the short 

 ciliary arteries, the long ciliary arteries, and the anterior ciliary arteries, 



