SYMMETRY IN TRANSPLANTED LIMBS 29 
6. Summary of the results of heterotopic transplantations. A 
survey of all the experiments in this group brings out the following 
facts: 
Implanted in dorsodorsal orientation, a limb bud gives rise to 
an appendage of its original prospective asymmetry, whether 
placed on the same or opposite side of the body. Such appen- 
dages have a normal posture when placed on the same side of 
the body from which they were taken, but when placed on the 
opposite side they mirror approximately the limb of that side, 
though they often become rotated to cjuite different postures. 
Implanted in inverted (dorsoventral) position, a limb bud gives 
rise to an appendage of reversed asynnnetry whether placed on 
the same or opposite side of the body. When placed on the same 
side, such appendages mirror the normal limb of that side, but 
when grafted on the opposite side, they assume a posture approxi- 
mately identical with that of the limb of that side. 
Limbs implanted in any of the four positions here studied may 
produce reduplications. As far as it has been possible to deter- 
mine, the primary limb of the pair is then of the same side as a 
single limb would be according to the foregoing rules. The redup- 
licating limb has been found to be, with a single exception, the 
mirror image of the first. 
Limbs that are grafted in abnormal location have at best very 
incomplete function and are often apparently entirely immobile. 
They usually do not become so large as those that are implanted 
in normal location, and they show defects and evidences of atro- 
phy much more frequently. 
B. Limb buds implanted in natural location — orthotopic 
transplantation 
In these experiments the limb bud of the host was first removed 
and then either put back in place, or else a bud from another 
embryo was grafted into the wound. In all of the earlier cases 
the wound bed was not cleaned after removal of the bud, so 
that some cells from the host were left to mingle with the tissues 
of the transplanted limb rudiment. The later experiments, with 
