494 The Origin and Differentiation of the Lens 
Fig. 7. Experiment DL;. Embryo rana sylvatica killed 3 days after 
partial extirpation of the right optic vesicle. Transverse section through the 
small regenerated eye. There is no trace of lens formation. The normal 
left eye is like the one in figure 6. > 90 diameters. 
Fic. 8. Experiment DL,,. Embryo rana sylvatica killed 5 days after 
partial extirpation of the right optic vesicle. Transverse section through 
small regenerated eye and through the normal left eye. No trace of a lens 
is to be found on the right side. X 45 diameters. 
Fie. 9. Experiment DL... Embryo rana sylvatica killed 4 days after 
partial extirpation of the right optic vesicle. Transverse section through 
small regenerated eye. No traces of lens formation are to be found in the 
sections. Two sections caudal to this one the regenerated eye shows its 
attachment by a long optic stalk to the brain. The normal left eye is like 
the one in Fig. 77, experiment DF,,. > 90 diameters. 
Fie. 10. Experiment DF,,. Embryo rana palustris killed 5 days after 
partial extirpation of the right optic vesicle. Transverse section through 
small regenerated right eye. No traces of lens formation are to be found in 
the sections. It is attached to the brain by a long optic stalk. The normal 
left eye is like the one in Fig. 75, experiment DF,,. > 90 diameters. 
Fic. 11. Experiment dx,. Embryo rana sylvatica killed 3 days after 
partial extirpation of the right eye. Transverse section through the regen- 
erated right eye which is in contact by its outer layer with the ectoderm. 
(There is an artificial separation in the sections.) No traces of lens 
formation are to be found in the sections. The normal eye is like the one 
in Fig. 59, experiment DF,,. > 90 diameters. 
Fie. 12. Experiment DL... Embryo rana sylvatica killed 3 days after 
partial extirpation of the right optic vesicle. Transverse section through the 
small regenerated right eye which is in contact with the ectoderm by its 
outer layer. No traces of lens formation are to be found in the sections. 
The normal left eye is like the one in Fig. 6, experiment DL,,. xX 90 
diameters. 
Fic. 13. Experiment DF,;,. Embryo rana palustris killed 3 days after 
partial extirpation of the optic vesicle. Transverse section through small 
regenerated right eye which is in contact by its outer layer with the ectoderm. 
No traces of lens formation are to be found in the sections. The normal left 
eye is similar to that in Fig. 59, experiment DF, or DF,. X 90 diameters. 
Fic. 14. Experiment DF,. Embryo rana palustris killed 3 days after par- 
tial extirpation of the right optic vesicle. Transverse section through the 
small regenerated right eye which is in contact by a portion of its retinal 
layer with the ectoderm. There is a slight thickening of the inner layer of 
the ectoderm opposite the eye but separated from it by a thin layer of 
mesenchyme. The normal left eye is similar to that in Fig. 59, experiment 
DF,,. X 90 diameters. 
Fic. 15. Experiment DF,. Section through the lens-plate more highly 
magnified than in Fig. 14. >X 3860 diameters. 
Fie. 16. Experiment DL,. Embryo rana sylvatica killed 4 days after 
partial extirpation of the right optic vesicle. Transverse section through the 
caudal part of the small regenerated eye showing its connection with the 
brain. The normal left eye is similar to the one in Fig. 70, experiment DF,,. 
x 90 diameters. 
Fie. 17. Section through part of anterior end of the eye in experiment 
DL, showing its contact with the ectoderm by the retinal layer and the 
formation at the place of contact of a small lens-plate. (The separation of 
the eye and ectoderm in the figure is an artefact.) x 180 diameters. 
