14 
ROSS G. HARRISON 
when there is a double redupUcation, then the two mirror planes 
intersect at the bifurcation in a line perpendicular to the proximo- 
distal axes; i.e., so that with reference to the radioulnar and dorso- 
palmar axes the planes of reflection face one another (fig. 4). 
Considerable deviation from this rule has, however, been noted 
in certain cases, and the amphibians do not seem to follow 
it with the same regularitj' as the arthropods, according to 
Bateson.i" 
MP2(u) 
Pig. 4 Diagram of reduplication, sectional view. In A the mirror planes are 
radial {MPi) and ulnar {MP2), and a certain amount of coalescence between the 
primary and the anterior reduplicating members is shown, as in figure 3. In B 
the mirror planes are radiodorsal (MPi) and ulno pulnar {MP2). D, dorsal; 
PAL, palmar; R, radial; U, ulnar. 
EXPERIMENTAL 
.4. Limb buds implanted in abnormal location — heterotopic 
transplantations 
In nearly all of the experiments in this group the limb bud was 
implanted on the flank of the embryo at the ventral border of the 
myotomes between the region of the fore and hind limbs. In a 
few cases it was placed on the side of the head between the eye 
and the ear, but the grafts were absorbed in all of these except 
Op. cit., p. 552. 
