EXPERIMENTS ON THE FORE LIMB OF AMBLYSTOMA 441 
48, Rem. E. 52, and H. E. 6—-) show more or less complete sym- 
metrical reduplication of the hand (figs. 29, 30, and 31). An- 
other (Rem. E. 28) has only the first digit doubled externally 
(fig. 32), though the unusual thickness of the limb indicates 
partial internal reduplication. Near the shoulder there is a 
distinct nodule. The case of the single limb with spur (Rem. E. 
17) is interesting in that the spur developed out of a bud which 
grew posterior to the wound scar and which at first seemed to be 
the main limb. Anterior to the wound a second bud appeared, 
first noticed eight days after the operation. On the twelfth 
day it was still but a nodule, and not till the eighteenth day did 
it look like a regenerating bud. It finally developed into a 
normal limb of the proper laterality, the posterior bud remaining 
attached to it as a spur (fig. 33). The case with two independent 
limbs (H. R. E. 10—) is fundamentally similar to the foregoing. 
The main limb bud developed posterior to the wound. Later 
there appeared anterior to this a second bud. In this ease, 
however, the two buds remained permanently separate. The 
anterior one gained over the posterior and became a normal limb 
of proper laterality with good function (fig. 34). The posterior 
one remained somewhat defective (second digit short and ulnar 
digits undeveloped), and when last examined alive, thirty-eight 
days after operation, it showed no movement. The remarkable 
feature of this case is that both limbs are right-handed, as was 
probably true of the spur case also, though the spur is too de- 
shoulder; thirty-one days after operation. Figure 33. Experiment Rem. E. 
17 (anterior half removed); hand foreshortened dorso-ventrally; S, spur repre- 
senting a duplicate limb; forty-three days after operation. Figure 34. Experi- 
ment H. R. E. 10 —(removal of anterior half); two left limbs; ANT7., anterior 
member, developed secondarily from anterior border of wound; POST ’., posterior 
member developed from the remaining half of the limb bud; forty days after op- 
eration. Figure 35. Experiment Rem. E. 18 (posterior half removed); radial 
digit reduplicated (D); limb amputated and preserved twenty-seven days after 
operation, followed by regeneration of normal limb (fig. 37 6). Figure 36. Ex- 
periment Rem. E. 16 (central portion removed); reduplicated second digit (2D); 
twenty days after operation. Figure 37. Experiment Rem. E. 18 (posterior 
half removed); A, normal left limb, B, normal right limb, regenerated after 
amputation of abnormal limb shown in figure 35; thirty-three days after ampu- 
tation. 
