51J: Experimental Studies on the Origin of the Lens in Amphibia 



B. Can the optic vesicle stimulate lens-formation from ectoderm other 

 than that which normally gives rise to the lens ? 



Is THERE A Special Predetermined Area of the Skin avhich 

 MUST BE Stimulated by the Optic Vesicle in order that a 

 Lens may arise? 



Experiment -Di^so- 

 Two days after the operation the embryo was killed. The sections 

 show a fair sized regenerated eye with a lens still broadly adherent to 

 the inner layer of the ectoderm and continuous with it, see Fig. 5. This 

 lens is about 50/x in diameter while the normal one on the uninjured 

 left side is about 7(.V Jn diameter, and completely separated from the 



Fig 11. ■ Fig. 13, 



Fig. 11. Experiment DFj,;. Transverse section through the transplanted eye. X 45 



diameters. 

 Fig. 12. Experiment DFj,-,. Section through the lens of the transplanted eye. X 300 



diameters. 

 Fig. 13. Experiment DFsn. Section throug-h the transplanted eye showing an early stage 



of lens-formation. X 300 diameters. 



ectoderm. Figure 11 through the transplanted eye, is from a section 

 130^ caudal to the section indicated in Fig. 5. Here the large irregular 

 transplanted eye lies close to the ectoderm, the inner layer of which is 

 thickened and bent into a lens-like process about 40/a in diameter. 

 The cells of this lens are continuous with those of the inner layer as 

 will be seen in Fig. 12. This experiment alone is sufficient to demon- 

 strate that the optic vesicle can stimulate lens-formation from strange 

 epithelium and that there is no predetermined area of the skin which 

 must be stimulated in order that a lens mav arise. 



