SYMMETRY IN TRANSPLANTED LIMBS 3 
affords a means of studying this question in any organ or part 
that in the adult lacks a plane of symmetry. It was with this 
purpose in view that the present experiments with the lunbs of 
Ambly stoma were begun. Limb buds were implanted in both 
normal and abnormal location, oriented in various ways with 
respect to the main axes of the embryo-host, and the form and 
posture of the resulting limbs were studied. 
It became evident, after the first experiments were made, that 
the rudiment of the fore limb behaved differently from the audi- 
tory vesicle, no matter whether Streeter's original interpretation 
or Spemann's was accepted as correct. While it was found that 
a certain tendency did exist for inverted limb buds to rotate back 
to normal posture during development, this was not the usual 
result, nor did the rotation take place in the sense meant by 
Streeter in his later publication ('14). Furthermore, many 
irregularities of development were produced by the operations, 
due largely to the power of the limb rudiment to duplicate itself 
by budding.i Qj^ i\^q other hand, it often occurred that buds 
transplanted from one side of the Jjody to the other developed in 
harmony with their new surroundings, a right limb bud, for ex- 
ample, placed on the left side, giving rise to a normal left limb. 
The earlier experunents which were made in 1911 and 1912 led 
to no satisfactory general conclusion, so that publication of the 
work was deferred pending further investigation. Subsequently 
numerous additional experiments were made, in which more ef- 
fective precautions against regeneration of the limbs from the 
host were taken.- The situation began to clear when in some of 
the cases in which the asymmetry of the limb was reversed by 
1 Cf. Barfurth ('94), who showed that supernumerary limbs could be produced 
in amphibians by regeneration after irregular amputation; Tornier ('05), who 
obtained multiple appendages by cutting into the limb bud of tadpoles; Braus 
('04, '05, and '09) and Harrison ('07), who found that transplanted limb buds 
frequently give rise to double limbs. 
2 The first experiments were reported to the National Academy of Sciences 
in November, 1912, at the New Haven meeting. Later reports were made before 
the American Association of Anatomists in December, 1915 ('16), and before the 
American Society of Zoologists in the following year ('17 a). The main results 
have been stated somewhat more fully in the Proceedings of the National Acad- 
emy ('15 and '17 b). 
