EXTIRPATION OF ORGAN ANLAGEN 2hj 



THE EYE FIELD OF THE NEURULA 



Manchot (I929), Adelmann (1950) and Mangold (1951) have shown that the two eye fields 

 are located close together near the median line of the anterior medullary plate of stage 

 #1*^ or #15 of the Urodela or stage #1^ of the Anura. The eye field extends beyond the 

 ultimately realized eye area, and extirpations and transplantations often result in pro- 

 ducing accessory eyes. 



Attempt to extirpate the eye forming area of the right eye alone. With glass needles 

 out deeply along lines indicated on the accompanying diagram, exposing the archenteron 

 beneath. Bemove the ectoderm and the substrate of this area while the embryo is in 10^ 

 Standard Solution and allow it to heal completely before gradually returning it to the 

 full strength Standard Solution. It will be necessary to operate on a number of embryos 

 because survival ia low. 



Variations of this extirpation should be in the direction of widening the area toward 

 the left aide; moving the area toward the mid-line; removing the epidermis with and with- 

 out the substrate. (See section on Eye Field Operations.) 



Sketch (photograph) immediately Sketches (photographs) of 

 after extirpation subsequent development 



