EXPERIMENTS ON THE FORE LIMB OF AMBLYSTOMA 449 
TABLE 8 
Showing effect of removal of limb mesderm 
CASES REGENERATED CASES NOT REGENERATED 
SIZE OF WOUND Healing of wound Healing of wound 
Total Total 
Good Fair Poor Good Fair Poor 
BAS OMMUEES§oyocAeagrt varus wie tik 1 1 1 3 2 2 
Te SOMIGES one seis eke 0 id 1 
A EESOMMGESS Soe eee 0 1 1 2; 
ABS OIMMUGES aa sete ete wees 0 2 2 
ROCA rene Renan 1 1 1 3 3 Ah G 
* In the table previously published (Harrison, ’15, p. 540) in the first column 
fifth line read 34 instead of 33. 
While the number of cases is not large, it is beyond doubt that 
the presence of the normal ectoderm over the denuded limb re- 
gion no more incites the development of a limb than does the 
presence of ectoderm from a distant region. 
TRANSPLANTATION OF THE MESODERM 
Transplantation of the whole limb bud, ectoderm and meso- 
derm, results, as is well known, in the development of a limb in 
the new position. Transplantation of one or the other of the 
two layers should afford additional evidence, more cogent than 
that already given, as to the potency of the several layers in 
determining the development of the appendage. Only one of 
these experiments, the transplantation of the mesoderm, has 
been tried; the negative results recorded with reference to the 
ectoderm in the previous section are thought to be sufficient 
evidence from that side. 
In order to transplant or inoculate the mesoderm into some 
other region of the body, a pocket is first made under the skin 
of the embryo by sticking the points of a pair of fine scissors 
obliquely through the ectoderm and slightly opening them. The 
position chosen for this pocket was in most cases the flank of 
the embryo at the lower border of the muscle plates. In four 
cases, all of which resulted negatively, it was made above the 
