EXPERIMENTS ON THE FORE LIMB OF AMBLYSTOMA 439 
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Figs. 21 to 28 Effect of removal of portions of the limb bud (continued). In 
the double figures A represents the limb of the unoperated and B that of the 
operated side. In all cases lateral view. XX 17. Figure 21. Experiment Rem. 
E. 2 (removal of posterior half); upper arm unoperated limb (A) much fore- 
“shortened; operated limb (B) generally less advanced in development, and with 
~ abortive first digit’ (1); seventeen days after operation. Figure 22. Experi- 
ment Rem. E. 7 (removal of posterior half); digits of normal limb (A) foreshort- 
ened in part; first digit of operated limb abortive; twenty-six days after opera- 
tion. Figure 23. Experiment Rem. HE. 1 (removal of ventral half) ; unoperated 
(A) limb not so long as operated (B); which has only one long digit; twenty-nine 
days after operation. Figure 24. Experiment Rem. E. 9 (central portion re- 
moved); both limbs foreshortened; unoperated limb further advanced, but both 
show defect of first digit; twenty-six days after operation. Figure 25. Experi- 
ment H. E. 18 — (dorsal half removed); limb of operated side has short second 
digit (2); eighteen days after operation. Figure 26. Experiment H. R. E. 33 — 
(removal of posterior half); second digit (2) is abortive and fused with the 
first (1); third digit well developed; twenty-one days after operation. Figure 27. 
Experiment Rem. E. 3 (anterior half removed); operated limb somewhat less 
developed than normal; syndactyly of digits 1 and 2; twenty-seven days after 
operation. Figure 28. Experiment H. HE. 28 — (removal of posterior half) ; well- 
developed limb with syndactylous first and second digits; twenty-eight days 
after operation. 
