138 



S. R. DETWILER 



Case AA2S7.^. In this experiment, which was carried out under 

 conditions indicated in table 1 B, the development of external 

 gills was completely suppressed and two limbs of the same 

 laterality developed in the heterotopic position (fig. 17). From 

 external observations on the developing larva it was impossible 

 to determine whether both members of the double limb developed 



16 17 



Fig. 16 Graphic reconstruction of segmental nerve supply to transplanted 

 right anterior limb in case AA2S25 (fig. 14). Limb occupies a position approxi- 

 mately two and one-half segments anterior to the normal. Arrow A indicates 

 level of transplanted limb; arrow B designates normal limb level. X 25. 



Fig. 17 Dorsal view of case AA2S73, showing absence of gills and presence of 

 two limbs of same laterality developed from anomalous reduplication of the 

 transplanted rudiment. Experiment carried out under conditions indicated in 

 table 1 B (fig. 3). X 5. 



from the transplant or whether the caudal member developed 

 from an unremoved portion of the original rudiment. The limb 

 bud which developed into the anterior appendage was the first to 

 appear. This was soon followed by a second bud which de- 

 veloped into the caudal member. The fact that the final posi- 

 tion of the latter was approximately two segments anterior to the 

 normal position suggested that it developed from the transplanted 

 rudiment. Moreover, examinations of sections showed that its 



