Warren Harmon Lewis 



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right optic vesicle which are in contact with the ectoderm are not the 

 ones which would have normally come in contact with the skin. Com- 

 pare the sizes of the right and left eyes in Fig. 37, which is drawn in a 

 plane that passes through the center of each eye. 



Fig. 37. Fig. 39. 



Fig. 37. Experiment IV,. Section through about the center ot both eyes. B, brain, i, 

 left. L', right lens. OF, right optic vesicle. X about 70 diameters. 



Fig. 38. Experiment IVjo. Outline of tadpole killed 11 days after the operation. Drawn 

 in xylol, t, transplanted eye. r, regenerated eye. X 8 diameters. 



Fig. 39. Experiment I Vio. Section through about the center of both eyes. X 45 diameters. 



Experiment IVj^^. 



The skin flap of an embryo of E. palustris of stage II was turned 

 forward and the optic vesicle cut off close to the brain and consequently 

 that portion of the optic vesicle which would later have become adherent 

 to the skin and stimulated the formation of a lens was entirely removed. 

 Eleven days after the operation the tadpole was killed. Eegeneration 

 of the eye had taken place from that portion of the optic vesicle still 

 attached to the brain wall and a small but fairly normally shaped optic 

 cup with a lens resulted, see Figs. 38 and 39. The regenerated optic 



