Fig. 30 Enlarged drawing of a horizontal section through the center of the 

 lens and fovea of the eye of the adult sparrow. Outlined with camera. /, nerve- 

 fiber layer; 2, ganglion-cell layer; 3, inner molecular layer; 4, inner nuclear layer; 

 5, outer molecular layer; 6, outer nuclear layer; 7, rod and cone layer; 8, pig- 

 ment layer; a, artery; B, bony portion of orbit; Br, location of Briicke's muscle; 

 C, location of Crampton's muscle; Ch, chorioid; Co, cornea; Cj, conjunctiva; 

 Cp, ciliary processes; Cs, canal of Schlemm; Ep, epithelium; F, feather follicle; 

 Fov, fovea; Hg, Harder 's gland; I, iris; L, lacrimal gland; Ld, lower lid; Ls, 

 lenticular portion of lens; M, location of Miiller's muscle; MP, median plane 

 of head; n, nerves; Na, nasal side of eye; Nc, nictitating membrane; 0, orbicu- 

 laris muscle fibers of lid; Ob s, superior oblique muscle; Pc, pars ciliaris retinae; 

 q, quadratus muscle; R-D, relative diameters of eye of man, Mn, and sparrow, 

 Sp; R ex, rectus externus; R inl, rectus internus; Rp, ring-like or annular pad of 

 lens; Rs, rectus superior; S, scleral plates; Scl, sclera, the dotted part shows the 

 cartilage portion; Sc, secretion in the lenticular cavity; Sp, space between the 

 retina and the chorioid due to shrinkage in the hardening process — an artefact; 

 T, temporal side of eye. 



400 



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