Warren Harmon Lewis 



511 



On the left or normal side is a large, well-formed optic cup and lens, 

 but on the right side there is not a trace of a lens or of a change in the 

 epithelial cells from which the lens would have arisen had the condi- 

 tions remained normal. The transplanted optic vesicle had been pushed 

 somewhat deeply beneath the skin into the cephalic end of the Wolffian 

 body caudal to the optic capsule (see Fig. 7). An examination of the 

 section shows that some of the brain adjoining the optic vesicle was cut 

 off and transplanted with it. There is no trace of a lens near this trans- 

 planted optic vesicle. 



Of twenty-one embryos of the series DF and lYi, killed five days after 

 the operation, fourteen have regenerated eyes and seven no traces of 

 regenerated eyes or lenses. Of the fourteen regenerated eyes seven are 

 more or less superficial and have 

 lenses, the remaining seven are 

 deeply buried in the mesenchyme 

 and of these six show no traces of 

 lenses. One of the deeply situated 

 regenerated eyes is quite small but 

 has a lens which is still attached l:)y 

 a long narrow pedicle to the inner 

 layer of the ectoderm (see Fig. 8). 

 The sections are cut obliquely to this 

 pedicle and in Fig. 8 it is drawn 

 from a flat reconstruction of the sev- 

 eral sections through which it passes. 



One embryo, killed five and one-half days after the operation, shows 

 a deeply placed regenerated eye without trace of a lens. 



Of eleven experiments in which the embryos were killed seven days 

 after the operation, ten show regenerated eyes with lenses while one 

 lacks the regenerated eye and lens entirely. 



Three embryos, killed eight days after the operation, show large 

 regenerated eyes with lenses. 



Two embryos were killed nine daj-s after the operation, both showing 

 regenerated eyes, superficially situated, but in one the lens is absent. 



Two embryos were killed eleven days after the operation, one shows 

 a regenerated eye with a lens, the other, experiment IV3, lacks entirely 

 an eye or lens in the normal place on the right side. 



Experiment IV^. 

 The embryo of E. palustris was experimented on as described above 

 and killed 11 davs after the operation. There is no sign of an eye or 



Fig. 8. Experiment I V,v Section through 

 the regenerated eye. X 33 diameters. 



