Warren Harmon Lewis 517 



the section in Fig. 16. The irregular transplanted eye lies between the 

 otic capsule and the regenerated eye. The transplanted eye is quite 

 superficial and at the place where it touches the ectoderm there is de- 

 veloping a small lens, about 45/x in diameter which is still broadly adher- 

 ent to and continuous with the inner layer of the ectoderm. See Fig. 15. 

 The section seen in Fig. 1-4 is cut obliquely and shows on the opposite 

 side the normal left eye with a lens about 135 fx in diameter. Here as in 

 experiment DFgg two lenses are developing on the same side of the head, 

 one in the normal position for the regenerated eye and the other some 

 distance caudal to this for the transplanted eye. 



Experiment DF^.. 



As in the preceding, the embryo was killed four days after the opera- 

 tion. The regenerated eye, deeply situated in the mesenchyme, consists 

 of an optic stalk with a small knob of cells at the end, see Fig. 17. 

 There is no sign of a lens in its neighborhood. The transplanted eye 

 is large and superficially situated between this regenerated eye and the 

 otic capsule. It has two lenses. One of them is quite small, 30/i, in 

 diameter and still attached to the inner layer of the ectoderm, see Fig. 18. 

 Fig. 19, from a section lOO/x cephalad to the section of Fig. IS, shows the 

 second lens and a portion of the same eye shown in Fig. 18. This lens 

 is about 60/A in diameter and is separated from the skin by a layer of 

 mesenchyme. It is most probable that this lens came from the overlying 

 ectoderm, as it shows some differentiation. There are no signs of its 

 having arisen from the optic cup and the lens is farther from the edge 

 of the optic cup than from the skin. Experiments DF^g, see Fig. 23, 

 and DF44, see Fig. 35, illustrate clearly how such a lens might have 

 arisen. 



Experiment DF.^^. 



The embryo was killed four days after the operation. The regener- 

 ated eye is small and deeply situated, much as in experiment DF4-. It 

 shows no traces of a lens in its neighborhood or in connection with the 

 overlying skin. The transplanted eye is large and quite regularly in- 

 paginated, see Fig. 20. It lies between the regenerated eye and the otic 

 capsule. Lying between the outer layer of the optic cup and the skin 

 is a small lens about 30/^ in diameter. From its position and the condi- 

 tion of the overlying ectoderm it seems likely that it has been recently 

 derived from the ectoderm. If it had been derived from the optic cup 

 we should hardly expect it to lie in this position. A slight irregularity 

 on the superficial surface of the lens, a small projection from the over- 



