EXTIRPATION OF ORGAN ANLAGEN 



253 



RANA RPIENS 



LENS AMJEE 



STAGE 13 - 14 



STAGE 17 

 (34 HRS. LATER) 



THE OPTIC VESICLE 



The optic vesicles of both the Anura and the Urodela are capable of regulation. This 

 means that if the entire eye field is not removed, there may be a degree of restoration 

 or regeneration of the excised parts. No 

 regeneration occurs when the entire optic 

 vesicle is removed, indicating that the eye- 

 forming properties do not extend beyond 

 the limits of the prospective eye forming 

 area. 



The above statements can be verified by 

 removing only the outer retinal portion of 

 the optic vesicle in some embryos and the 

 entire optic vesicle in others, examining 

 by dissection and by histological (section- 

 ing) technique after a minimum of a week 

 of recovery and development at laboratory 

 temperatures. 



The Anuran embryos at stage #17 (R. syl- 

 vatica and palustris preferable to pipiens) 



Extirpation of the retina and the entire 

 optic vesicle Rana: stage #17 



