168 Lens-Formation from Strange Ectoderm 
Fic. 63. Experiment DL,,. Optic vesicle transplanted anterior to otic. 
vesicle. Embryo killed 4 days after the operation. Section through trans- 
planted eye and lens. They are about as large as normal and the optic cup 
is as far differentiated. The lens is not so far differentiated as normal and 
is irregular, showing at its caudal end evidence of attachment to the ecto- 
derm (see Fig. 64). > 90 diameters. 
Fic. 64. Experiment DL,,. Section through caudal end of lens, edge of 
optic cup, and ectoderm. The latter shows place where lens was attached. 
A few sections caudal to this-one an ectodermal process continues off from 
the lens into the mesenchyme. X 90 diameters. 
Fic. 65. Experiment DL,,. Section through normal eye and lens. 
Fic. 66. Experiment DL,. Embryo killed 4 days after the operation. 
Section caudal to the otic vesicle through transplanted eye, etc. On the 
median side of the irregular eye is an irregular mass of ectoderm with two 
cavities. X 100 diameters. 
Fic. 67. Experiment DL,,. Ectodermal mass from the above section show- 
ing beginning transformation into lens on the side towards the retinal portion 
of the eye. X 200 diameters. 
Fic. 68. Experiment DL,;. Embryo killed 4 days after the operation. 
Section through transplanted eye which lies caudo-ventral to the otic vesicle. 
In the cavity of the irregular eye is an irregular mass of ectoderm contain- 
ing several cavities and small pigment masses. There are only slight signs 
of its differentiation into a lens. The ectoderm in this region was evidently 
injured, a loop of ectoderm cut in section at a crosses over the region of the 
eye. > 100 diameters. 
Fic. 69. Experiment DL,. Embryo killed 3 days after the operation. 
Section through transplanted eye which lies ventral to the otic vesicle. On 
the median side of the transplanted eye is a large irregular mass of ectoderm 
and the part in contact with the eye seems to be undergoing transformation 
into lens tissue. > 100 diameters. 
Fic. 70. Experiment DL,,. Optic vesicle transplanted anterior in the otic 
vesicle. Embryo killed 4 days after the operation. Section through trans- 
planted eye and lens. In this embryo an ectodermal strand extends from 
the ectoderm to the pharynx, only a small portion of it was in the section, 
the rest of it has been projected into the section from the neighboring sec- 
tions. The lens has probably arisen from this strand and there is a slight 
indication on the process of the place where the lens was pinched off. Ph, 
pharynx wall. X 90 diameters. 
