ORGANS OF SPECIAL SENSE 273 
T2715 
ab. CH. 
Corn. — 
Fie. 159. — Frontal section of the eye of an eight day chick. 
ant. ch., Anterior chamber of the eye. ch., Choroid coat.  cil., Ciliary 
processes. Corn., Cornea. 1. e. 1., Lower eyelid. n. m., Nictitating mem- 
brane. olf., Olfactory sac. op. n., Optic nerve. o. s., Ora serrata. p., 
Pigment layer of the optic cup. post. ch., Posterior chamber of the eye. 
ret., Retina. scl., Sclerotic coat. sel. C., Sclerotice cartilage. u.e. 1., Upper 
eyelid. 
thinner than in the ciliary region. The mesenchyme overlying 
the iris early becomes condensed to form the stroma of the iris; 
the epithelia form the uvea of the developed iris (Fig. 159). 
The muscles of the iris (sphincter pupille) are stated by 
