500 The Origin and Differentiation of the Lens 
Fie. 42. Experiment DF,;. Embryo rana palustris killed 3 days after 
partial extirpation of the right optic vesicle. Section through regenerated 
eye and solid lens-sphere. The latter is separate from the ectoderm. xX 90 
diameters. 
Fic. 43. Experiment DF,;. Section through normal left eye and lens 
vesicle. > 90 diameters. 
Fig. 44. Experiment DF,,. Embryo rana palustris killed 3 days after the 
operation (see Figs. 20 and 21). Section through edge of normal left eye, 
edge of lens, lower edge of optic cup and ectoderm showing small lens-bud- 
like structure attached to the inner layer of the ectoderm. Probably place 
where lens was pinched off. X 360 diameters. 
Fie. 45. Experiment DL.,. Embryo rana sylvatica killed 4 days after 
extirpation and transplantation of the right optic vesicle. Section through 
lens-like bud of the inner layer of the ectoderm. It is near the otic vesicle 
but not near either the normal lens area or near the transplanted eye. It 
was probably caused by injury to the ectoderm during the transplantation of 
the eye. X 180 diameters. 
Fic. 46. Experiment DL,,. Embryo rana sylvatica killed 3 days after 
partial extirpation of right eye. Section through lens-like bud of inner 
layer of ectoderm, anterior to otic vesicle, and is probably from wound 
caused in making skin flap. x 180 diameters. 
Fig. 47. Experiment DF,,. Embryo of rana palustris killed 5 days after 
partial extirpation of right eye. Regenerated eye has two lenses. Section 
through lens-like bud of the inner layer, anterior to regenerated eye, and is 
probably from an injury to the skin flap. XX 180 diameters. 
Fie. 48. Experiment DL... Embryo of rana sylvatica killed 4 days after 
the operation. Section through “lens-like bud’ which has arisen between 
the normal lens-forming region and the otic vesicle about in the region of 
the wound of incision. X 360 diameters. 
Fie. 49. Experiment DL,,. Embryo rana sylvatica killed 5 days after the 
operation. Section through long lens-like bud near otic vesicle. It is prob- 
ably from injury to the ectoderm made during the transplantation of the 
eye. xX 90 diameters. 
Fic. 50. Experiment DL,,. Distal end of lens-like bud. X 360 diameters. 
Fic. 51. Experiment DL,,. Embryo of rana sylvatica killed 3 days after 
the operation. Section through solid ectodermal spherical mass which has 
probably arisen from the ectoderm. It is located caudal to the normal lens- 
forming area about in the region of the wound of incision. x 360 diameters. 
Fic. 52. Experiment DL,. Embryo of rana sylvatica killed 5 days after 
the operation. Section through ectoderm and small lens-like vesicle, located 
caudal to the normal lens-forming area about in the region of the wound of 
incision. The ectoderm over the vesicle shows still evidences of the origin 
of the vesicle and dips down into the mesenchyme. X 360 diameters. 
Fic. 53. Experiment DL,,. Embryo rana sylvatica killed 5 days after 
transplantation of optic vesicle into otic region. Section through otic vesicle, 
transplanted eye, and ventral to it a small lens-like vesicle, probably from 
injury to the ectoderm. X 90 diameters. 
Fig. 54. Experiment DL,,. Lens-like vesicle more highly magnified. 
xX 360 diameters. 
