SYMMETRY IN TRANSPLANTED LIMBS 
63 
C. Superposed limb buds 
In the preceding study of transplanted limbs certain experi- 
ments were described, which showed that the mesoderm from 
two limb buds, when fused together, would develop into a single 
normal limb. At first larger than normal, the size of such a 
limb is soon regulated. In the former communication only those 
experiments were considered in which the orientation of the 
superposed bud was normal (hom.dd). The effect of the orienta- 
tion of the graft will now be taken up, 
TABLE 3 
Superposed limbs. Sximviary of results 
OPERATION 
NUMBER OF 
EXPERIMENTS 
NORMAL 
SINGLE LIMBS 
NORMAL SINGLE 
WITH REDUCED 
REDUPLICATION 
REDUPLICATED 
Total 
Posi- 
tive 
Num- 
ber 
Per 
cent 
Num- 
ber 
Per 
cent 
Num- 
ber 
Per 
cent 
Horn, dd 
Horn, dv 
Het. dd 
Het. dv 
5 
5 
6 
9 
5 
5 
5 
5 
5 
1 

5 
100 
20 
00 
100 


1 

00 
00 
20 
00 

4 
4 

00 
80 
80 
00 
Total 
25 
20 
11 
55 
1 
5 
8 
40 
The experiments are summarized in table 3. There were 
twenty-five operations, of which twenty are available for the 
analysis. Two of the combinations, the ones which the ordi- 
nary transplantations have shown to be harmonic (homopleural 
dorsodorsal and heteropleural dorsoventral) yielded only normal 
appendages (ten cases). The two disharmonic' combinations 
(homopleural dorsoventral and heteropleural dorsodorsal) yielded 
reduplications in nine cases out of ten. One case, in which one 
member of the duplicate limb was reduced to a spur, is included 
among the reduplications. 
13. Homopleural transplantations, dorsodorsal orientation. In 
this group development went forward with a minimum of dis- 
turbance. The only abnormal feature to note is the large size 
of the double bud in certain individuals. In several of the cases 
THE JOURNAL OF EXPERIMENT.^L ZOOLOGY, VOL. 32, NO. 1 
