162 Lens-Formation from Strange Ectoderm 
Fic. 44. Experiment DL,,. Optic vesicle transplanted in the region of the 
otic vesicle. Embryo killed 5 days after the operation. Section through 
transplanted optic vesicle, otic vesicle, and medulla. The main part of the 
optic vesicle lies medial to the otic vesicle but the anterior end of the eye 
lies anterior to the otic vesicle and the eye and lens here are separated from 
the ectoderm by a thick layer of mesenchyme. Both lens and transplanted 
eye seem to be larger than normal, the optic cup is somewhat irregular but as 
far differentiated as normal; the lens, however, is not as far advanced. 
Compare with Fig. 43, which is similar to the normal eye. x 90 diameters. 
Fic. 45. Experiment DL,. Optic vesicle transplanted into otic region. 
Embryo killed 3 days after the operation. Section through transplanted eye, 
lens, otic vesicle, etc. Ventral to the transplanted eye is a large mass of 
transplanted brain tissue and connected with this a large mass of modified 
ectodermal tissue, a process from this at (a) is connected with a long strand 
of ectodermal cells which pass anteriorly between the otic vesicle and optic 
cup close to the lens, to the ectoderm anterior to the otic capsule (see Fig. 
46). The ectodermal mass is also attached to the ectoderm in the region (0) 
a few sections caudal to this one. Whether the lens has arisen from this 
long strand which lies near it or directly from the ectoderm is impossible to 
decide. The lens is much elongated with cavities at each end. X 100 
diameters. 
Fic. 46. Experiment DL,. Section through origin of ectodermal strand 
showing its continuity with the inner layer of the ectoderm. X 200 diame- 
ters. 
Fic. 47. Experiment DL,,. Optic vesicle transplanted into the region of 
the otic vesicle. Embryo killed 4 days after the operation. Section through 
transplanted eye and lens. They are separated from the ectoderm by mesen- 
chyme and the otic vesicle. The lens is somewhat irregular and is still 
attached to the ectoderm by a narrow pedicle (see Fig. 48). x 90 diameters. 
Fic. 48. Experiment DL,,. Flat reconstruction of the above lens made 
from several adjoining sections. It shows the narrow pedicle connecting 
the lens with the ectoderm and also a portion of the lens between one edge of 
the optic cup and the otic vesicle. > 90 diameters. 
Fic. 49. Experiment DL,,. Optic vesicle transplanted anterior to the otic 
vesicle. Embryo killed 4 days after the operation. Section through trans- 
planted eye and small lens-bud. The latter is attached to a large irregular 
ectodermal mass which has come from the inner layer of the ectoderm, prob- 
ably caused by injury to the ectoderm during the transplantation. xX 90 
diameters. 
