SYMMETRY IN TRANSPLANTED LIMBS 27 
limb bud developed into a long almost filiform structure, with* 
out digits, that grew posteriorly on the ventral side of the body 
not far from the midline. Twenty days after the operation a sec- 
ond bud was noticed dorsal to the original, and this developed 
into a somewhat peculiarly placed limb. The upper arm runs 
transversely and the palm of the hand faces dorsomedially (figs. 
33 and 34). This limb is clearly a left; i.e., its original prospective 
asymmetry has been reversed. It therefore constitutes an ex- 
ception to the rules, not only because of the position of the 
hand, but also because of its particular asymmetry ; for the original 
(filiform) member should have been reversed (a left), and the 
second one reversed back again to the original asymmetry. How- 
ever, the fact that the latter developed at such a considerable dis- 
tance from the original member, might be regarded as indicating 
that it was beyond its sphere of influence, perhaps having been 
split apart from it at an early stage, and that it remained there- 
fore as of the same side. Several cases of regeneration after 
extirpation of half buds and of transplantation of half buds gave 
analogous results (fig. 132). ^^ 
5. The shoulder-girdle in heierotopic transplantations. The 
limb-girdle in the hetrotopic transplantations is developed in 
more or less reduced condition, as was first shown by Braus ('09) 
in the anurans. Detwiler ('18) has studied this question in 
Amblystoma, and has found that the degree of development of 
the girdle is dependent upon the size of the graft and the region 
from w^hich it is taken, the scapula and suprascapula being local- 
ized in the tissue dorsal to the normal limb bud and the coracoid 
in that ventral to it.-^ The form of the reduced girdle derived 
25 Cf. Harrison, '18, p. 441 (Exp. Rem. E. 17 and H. R. E. 10), and page 135 
of the present paper (Exp. H. R. E. 20). 
-^ It is a curious fact that in the embryo the limb-girdle has undoubtedly 
the character of a mosaic, without totipotence of its parts, while in the adult 
Triton, according to Tornier ('06), Fritsch ('11), and Kurz ('12), a small portion 
of the shoulder-girdle can regenerate the whole, including the fore limb. Ac- 
cording to the two last-named investigators, even if the whole girdle is removed, 
it will be regenerated together with the free appendage. Kurz has found that 
this holds for both shoulder and pelvic girdles but that removal of the sacral 
portion of the vertebral column prevents regeneration. In the anurans, accord- 
ing to Braus ('06), there is considerable variation in the regenerative powers of 
the limbs in early stages. 
