4 The Origin and Differentiation of the Optic Vesicle 
Fic. 1. Experiment DF,.. Embryo rana palustris killed 17 days after 
transplantation of optic vesicle anterior to otic vesicle. Section through 
transplanted eye and lens. The ganglionic layer of the retina contains only 
a few scattered cells, otherwise the retina is quite normal, as in Fig. 2. No 
optic nerve was found. X 100 diameters. 
Fic. 2. Experiment DF,.. Section through part of normal retina, gan- 
glion layer a continuous layer one cell thick. X 100 diameters. 
Fic. 3. Experiment DF,,. Embryo rana palustris killed 19 days after 
transplanting grtic vesicle ventral in the otic vescile. Section through 
caudal end of eye showing very small extent of pigment layer and irregular 
arrangement of retina. r, r, small areas of rods and cones. m, m, m, outer 
molecular layer. > 100 diameters. 
Fic. 4. Experiment DF,,. Section showing irregular arrangement of 
above transplanted eye. No pigment layer. Rods and cones project towards 
a central cavity in which are a few masses of pigment. All the layers of the 
retina can be distinguished but irregularly distributed. Xx 100 diameters. 
Fig. 5. Experiment DF;,. Embryo killed 7 days after transplantation of 
the eye anterior to the otic vesicle. Section through transplanted eye. The 
pigment layer entirely surrounds the eye and dips down in the region of the 
pupil, which is entirely obliterated. The cup cavity is very small. Between 
the outer layer and the forming endothelial layer is a small abortive lens. 
The various layers of the retina are thicker than normal. X 100 diameters. 
Fic. 6. Experiment DD,,. Embryo killed 4 days after transplantation of 
the eye. Section through small piece broken away from the eye during the 
operation showing retinal and pigment cells. ™ 200 diameters. 
Fic. 7. Experiment DL... Embryo killed 5 days after transplantation of 
the eye caudal to otic region. Section through transplanted eye and lens. 
The eye is median to anterior end of Wolffian body and the ventral portion of 
it projects into the celom. The outer pigment is here wanting and the meso- 
thelial layer of the peritoneum also, so that the small rods and cones project 
directly into the celom. X about 200 diameters. 
Fic. 8. Experiment IV,,. Embryo killed 5 days after transplantation of 
optic vesicle caudal to otic vesicle. Section through irregular transplanted 
eye showing contact of pigment layer with the peritoneum (p) and also con- 
tact of the eye with the ectoderm (e). X 100 diameters. 
