SYMMETRY IN TRANSPLANTED LIMBS 39 
larger than usual (four somites in diameter), and it is possible 
that the reduplicating bud, growing from near its anterior border, 
was uninfluenced by the primary limb and hence was not mirrored. 
There remain for consideration those cases in which a single 
non-reversed limb developed. As in the other cases, the limb 
bud in these showed at first the consequences of abnormal orien- 
tation. When first observed it pointed more sharply laterally 
and more dorsally (less posteriorly) than normal. Two even 
pointed dorsally and slightly anteriorly. In the course of devel- 
opment the limb gradually changed its posture and ultimately 
came to a perfectly normal posture by a process of rotation at the 
shoulder-joint (figs. 56 to 59). Ten such cases were obtained, ^^ 
though in several of theni''^ it is possible that reversal may have 
been brought about by early reduplication and suppression of the 
original bud, as described in the next section (p. 49). In one of 
these^^ a supernumerary radial digit was present, but this is to 
be regarded as a case of hyperdactyly rather than one of mirrored 
reduplication. In one case^'' the limb which originally developed 
showed irregularities in the digits. The arm was then ampu- 
tated above the elbow, and the appendage which regenerated was 
in every respect normal. This case is of considerable interest in 
showing that the abnormal condition which produces reduplica- 
tion is not necessarily stamped upon the whole structure, but 
may be due to some local mechanical disturbance. 
In reviewing this group of experiments, it is clear that the first 
two results, i.e., single reversed limbs and most of the reduplica- 
tions, come under the same scheme. There is a primary reversal 
of asymmetry, without reduplication in the first case and accom- 
Figs. 56 to 59 Orthotopic transplantation; left limb bud inverted (horn. dr.). 
Limb reaches normal posture by rotation. Exp. I. E. 49. A", normal (right) 
limb; TR, transplanted (left) limb. 
Fig. 56 Eleven days after operation. 
Fig. 57 Twenty-one days after operation. 
Fig. 58 Thirty-eight days after operation. 
Fig. .59 Preserved specimen, killed at thirty-nine days. 
'' I. E. 49, 55, 69, 71, 73, 77, 84, 94, 99, and 101. "" I. E. 101. 
^8 For instance, I. E. 77. ^o I. E. 71. 
