444 Warren Harmon Lewis. 



EXPLANATION OF PLATES. 

 Plate I. 



Fig. I. Experiment XLVsae- Right optic cup and lens taken out shortly after separation of the 

 latter from the skin. Embryo killed 1 1 days after the operation. Figure from section through right 

 eye region. A bit of the optic cup with nerve is deeply buried near optic foramen. No traces of corneal 

 formation. The normal left side has a well developed cornea. X 80 diameters. 



Fig. 2. Experiment Mn4. Right optic cup and lens taken out at a somewhat later period than the 

 above, but before there were visible corneal changes. Embryo killed 12 days after the operation. 

 Figure from section through the right eye region. A small depressed area of corneal clearing is seen, 

 which is scarcely j'q the diameter of the normal cornea on the left side. X 80 diameters. 



Fig. 3. Experiment ME2. Right optic cup removed shortly before the separation of the lens from 

 the skin. Embryo killed 16 days after the operation. Figure from section through the right eye 

 region. The lens, much smaller than normal, is separated from the ectoderm by mesenchyme. There 

 are no corneal changes in the epidermis. On the left side the cornea is large and well formed. X 80 

 diameters. 



Fig. 4. Experiment VII361. A portion of the right optic cup cut away before corneal formation. 

 Embryo lulled 9 days after the operation. Figure shows irregular eye smaller than normal with cor- 

 respondingly small cornea. X 80 diameters. 



Fig. 5. Experiment VII3. Operation as above except that more of the optic vesicle was cut away. 

 Figure shows small eye and cornea. X 80 diameters. 



Fig. 6. Experiment MD4. Portion of eye cut away before lens formation. Embryo killed 12 

 days after the operation. Figure shows absence of lens, small eye with small cavity and pupil, and 

 corneal formation over the optic cup. ;< 80 diameters. 



