Warren Harmon Lewis 



509 



see Fig. 4. In experiment DFgg there is over the regenerated eye 

 a large lens about bOfx in diameter but still quite broadly adherent to 

 the ectoderm, see Fig. 5. The normal lens of the left side is about 

 70/i in diameter and shows considerable advance in differentiation. 



Fig. 4. Fir.. 5. 



Fig. 4. Experiment DF55. Transverse section through the middle of the regenerated eye. 

 X 45 diameters. 



Fig. 5. Experiment DF56. Transverse section through the middle of the regenerated eye. 

 X 45 diameters. 



Of four experiments of the series DF in which the embryos were 

 killed two and one-quarter days after the operation, the eyes have re- 

 generated sufficiently in each to reach the ectoderm and in each instance 

 there is a lens, still attached to the skin in three and detached in the 

 fourth. 



In sixteen embryos of the series DF, killed three days after the ope- 

 ]'ation, fourteen showed regenerated eyes of various sizes. Of these, eleven 

 touch, or nearly touch the skin and ten of them have lenses and three 

 of the nine are still attached to the ectoderm. Three of the regenerated 

 eyes are small and separated from the ectoderm by a considerable layer 

 of mesenchyme and in these the skin shows no sign of lens-formation. 

 In two of the sixteen experiments no traces of regenerated eyes were 

 I)resent and there were no signs of lens-formation or of changes in the 

 ectoderm indicating where the lens would have arisen under normal 

 conditions with the eye present. 



Of twenty-two embryos of the series DF, killed four days after the 

 operation, twenty-one show regenerated eyes of various sizes. Of these 

 regenerated eyes nine touch or nearly touch the skin and have lenses, 

 three of which are still attached to the ectoderm. Seven of the regene- 



