112 ROSS G. HARRISON 
cate bud in these cases, having its asymmetry reversed and oc- 
cupying the right position, became a normally functioning fore 
limb, perfectly adjusted both functionally and structurally to 
its organic environment. 
15. Limb buds, taken from the opposite side of the body and 
miplanted with the dorsoventral axis inverted, so as to leave the 
anteroposterior axis in normal relation, formed, with the excep- 
tion of one reduplication, single limbs, all of which were reversed 
These Imibs were often considerably retarded in development, 
but, as regards both function and form, they became perfectly 
adjusted to their new surroundings (rule 2). 
16. In the superposed grafts two limb buds are fused into one. 
In the two harmonic combinations normal single limbs arise. 
Though at first usually above normal in size, they soon become 
regulated in this respect. In the disharmonic combinations du- 
plex appendages were formed in a large majority of cases. One 
case of adjustment by rotation and one case of regulation by 
reduction of one member of a pair were found. 
17. In experiments with half buds there are sixteen combina- 
tions possible with the restrictions unposed by the character of 
the experiment. In addition to the two pairs of attributes of 
operation common to all of the experunents {ho7n. or het., dd or 
dv) there are three others: the bud may be halved vertically or 
horizontally; the anterior or the dorsal half, or the posterior or 
the ^^entral half may be transplanted, the other remaining intact; 
two like halves or two unlike halves may be united. An analysis 
of the results shows that no one of these qualities in itself deter- 
mines the result, but that it is the harmonic or disharmonic 
character of the combination that determines whether normal or 
reduplicated appendages arise. Thus, allowing for differences 
in the number of experunents in each class, 93.4 per cent of the 
harmonic combinations produced normal limbs, while in the 
disharmonic groups about that same proportion produced redu- 
plications, of which, however, a considerable number were regu- 
lated secondarily through resorption of the disharmonic member. 
18. That the Imib bud is an equipotential system is shown by 
the fact that a normal limb may develop after the following oper- 
