496 The Origin and Differentiation of the Lens 
Fic. 18. Experiment DF,;. Embryo rana palustris killed 4 days after 
partial extirpation of the right optic vesicle. Section through the small 
regenerated eye showing where outer layer and small corner of the retinal 
layer were in contact with the ectoderm. A small lens-bud is attached here 
to the inner layer of the ectoderm. The normal left eye is similar to the 
one in Fig. 77, experiment DF,,;. > 90 diameters. 
Fic. 19. Lens-bud in the above experiment DF,, more highly magnified. 
< 360 diameters. 
Fig. 20. Experiment DF,,. Embryo rana palustris killed 3 days after 
partial extirpation of the right optic vesicle. Section through anterior por- 
tion of regenerated eye showing contact of edge of the cup with the ectoderm 
and the formation of a small lens-bud from the inner layer of the ectoderm. 
The normal right eye is similar to that in Fig. 42 or 68, experiment DF,,; or 
DF,. X 90 diameters. 
Fig. 21. Lens-bud in above experiment, DF,, more highly magnified. 
x 360 diameters. 
Fic. 22. Section through caudal portion of same eye, experiment DF,,, 
show small cup separated from the ectoderm by mesenchyme. X 90 
diameters. 
Fic. 23. Experiment DF, . Embryo rana palustris killed 3 days after 
partial extirpation of the right optic vesicle. Section through caudal end 
of regenerated eye, it is separated from the brain by the anterior end of the 
transplanted eye and apparently pushed against the ectoderm where there is 
a small lens-bud attached to the inner layer of the ectoderm. The retinal 
portion of the regenerated eye is in contact with the lens-bud. The normal 
left eye is similar to the one in Fig. 42, experiment DF,;. X 90 diameters. 
Fic. 24. Experiment DF,. Lens-bud more highly magnified. x 360 
diameters. 
Fig. 25. Experiment DF,. Embryo rana palustris killed 4 days after 
partial extirpation of the right optic vesicle. Section through the small 
regenerated right eye. It is separated from the ectoderm by a thin layer of 
mesenchyme. There is a small lens bud attached in the inner layer of the 
ectoderm. The normal left eye is similar to that in Fig. 61, experiment DF, . 
x 90 diameters. 
Fig. 26. Experiment DF,. Lens-bud more highly magnified. x 360 
diameters. 
Fic. 27. Experiment dx,. Embryo rana sylvatica killed 3 days after par- 
tial extirpation of the right optic vesicle. Section through small regenerated 
right eye and small lens-bud, the latter is still attached to the ectoderm but 
is separated from the optic cup by mesenchyme. X 90 diameters. 
Fic. 28. Experiment dx,. Caudal end of regenerated eye in contact with 
the ectoderm by the outer layer. No signs of lens formation here. X 90 
diameters. 
Fic. 29. Experiment dx,. Section through normal left eye. X 90 
diameters. 
Fic. 30. Experiment dx,. Embryo rana sylvatica killed 3 days after par- 
tial extirpation of the right eye.. The regenerated eye is about the size and 
shape of the one in Fig. 27. Its caudal end does not show the outer layer 
cells. Section through caudal end of the eye and lens-bud. A thin layer 
of mesenchyme separates them. The normal left eye is similar to the one in 
Fig. 29. X 360 diameters. 
