IX 



EYE 



341 



ect 



thai 



\m\\m\ 



Fig. 142. 



Development of the eye as seea in transverse sections of Fowl embryos. A, Latter half of second 

 clay of incubation ; B, end of second day ; C, 24- days ; D, 3 days ; E, latter half of fifth day. 

 ect. External ectoderm; I, lens; o.r, rudiment of eye; o.s, optic stalk; ^./, pigment layer; 

 r retina ; thai, wall of thalamencephalon, [The gap below the lens in D is due to the section passing 

 through part of the choroid fissure. Each division of the scales represents -oi mm.] 



