62 ROSS G. HARRISON 
metry, Avhile the latter behaves m accordance with the rules 
governmg the asymmetry of transplanted limbs. In the dis- 
harmonic combinations the portions of the girdles derived, re- 
spectively, from the two sources may fuse together or may remain 
entirely separate. In the harmonic combinations they unite to 
form a single normal girdle. 
12. Summary of the results of orthotopic transplantations. The 
orthotopic transplantations develop according to the same rules 
as the heterotopic. In the homopleural dorsodorsal and the 
heteropleural dorsoventral groups rules 1 and 2 (p. 4) are very 
closely followed. In the former the limb buds, being right side 
up, retain their normal asymmetry; and in the latter, being upside 
down, they reverse it. In both groups this results in limbs which 
correspond to the side on which they are implanted (harmonic 
combinations). 
In the other two groups the primary single limbs which 
develop do not correspond to the organic environment, since 
the homopleural graft, when placed upside down, becomes re- 
versed, and the heteropleural graft right side up retains its origi- 
nal prospective asymmetry. In these combinations, which 
have been called disharmonic, single limbs are, however, the 
exception. It is here that rule 3 comes into play. Reduplica- 
tions occurred in 7 1 . 1 per cent of the cases in the homopleural dor- 
soventral group and in 80.6 in the heteropleural dorsodorsal. 
The former includes only one case of single limb reversed. In 
this class are also five cases of reversed single limbs, which are 
fundamentally the same as reduplications, the original limb 
having been suppressed or resorbed. The disharmonic relation 
thus augments immensely the tendency to reduplicate. In the 
case of the heterotopic grafts, on the contrary, the greater pro- 
portion of reduplications occurs in the harmonic combinations. 
This curious fact will be discussed below (p. 107). The ten cases 
of non-reversed single limbs which resulted from homopleural 
inverted buds are, as already pointed out, exceptional in that the 
limb regained its normal posture gradually during development 
by rotation at the base. 
