312 



REGENERATION 



Fig. 1. Amblystoma opacum larva (RV-21). 

 Total length 29 mm at time of limb rever- 

 sal. Photographed 64 days after reversal. 

 Tracing at lower right shows size and orien- 

 tation of three-digit reversed limb. Normal 

 right limb has completely regenerated. 

 Portions of right gills were amputated so that 

 they would not obscure limbs. Photograph 

 has been slightly retouched in order better 

 to show details. 



Fig. 2. Amblystoma opacum lar\'a (RV-42). 

 Total length 28 mm at time of limb re- 

 versal. Photographed 58 days after rever- 

 sal. Tracing at lower right shows size and 

 orientation of four-digit reversed limb. 

 Normal right limb has completely regen- 

 erated. Right gills were amputated so that 

 they would not obscure limbs. Photograph 

 has been slightly retouched in order better 

 to show details. 



Fig. 3. Graphic reconstruction of the skeleton of 

 a reversed limb of Amblystoma opacum 

 larva (RV-51). Point of attachment of limb 

 to body wall is at tlic top; 4 of the original 

 carpals (oc) are present. Limb has under- 

 gone regression so that only a small portion 

 of humerus (h) remains, articulating with 

 radius (r) and ulna (u). 



Fig. 4. Graphic reconstruction of the skeleton 

 of a reversed limb of Amblystoma opacum 

 larva (RV-59). Point of attachment of 

 limb to body wall is at the top; three of 

 the original carpals (oe) are present. At 

 the free end of the reversed limb has been 

 established a regenerate in which new car- 

 pels (c) and the skeletal components of 4 

 digits are being mapped out. 



Fig. 5. Graphic reconstruction of the skeleton 

 of the hand and wrist of a reversed limb of 

 Amblystoma opacum larva (RV-62). 

 Original proximal ends of radius (r) and 

 ulna (u) have fused. New carpals (c), 

 metacarpals (mc) and phalanges (p) are 

 present. 



(Courtesy of Dr. E. G. Butler, from 

 Jour. Morph. 96:265, 1955.) 



