28 ROSS G. HARRISON 
from the usual round di.sc (limb bud) is roughly triangular, as 
shown in the figure of Detwiler's model (his figure 28), with a 
ventral process projecting anteriorly, to be identified as a rudi- 
mentary coracoid, and a dorsal process, which includes the rudi- 
ment of the scapula. In the normally oriented grafts (homo- 
pleural dorsodorsal) these processes point anteriorly, with a 
single process projecting posteriorly slightly behind the glenoid 
cavity. This shows clearly in two cases." The question now 
arises whether the girdle follows the rules governing the asym- 
metry of the free limbs. The results, in the main indicate that 
such is the case, though the girdle developed is often so small 
and rudimentary, that it is not possible to determine to which 
side it belongs. In the inverted homopleural grafts, which give 
rise to reversed limbs, the girdle also seems to be reversed. This 
is true in four cases out of the five examined in serial sections. -^ 
Among the heteropleural dorsodorsal transplantations, five 
cases have been examined in sections. In two of them-^ with 
well-developed glenoid cavity, the girdle cartilage is mostly ven- 
tral and posterior to the joint. This probably represents a cora- 
coid with asymmetry corresponding to that of the free limb. One 
case,^° with the cartilage projecting both anteriorly and pos- 
teriorly from the cavity, gives no evidence as to the side to which 
it belongs. One is too rudimentary,''^ and one seems to have had 
its asjaiimetry reversed,^- though the limb is not reversed. In 
the two dorsoventral heteropleural transplants which have been 
studied in sections, the side to which the girdle belongs cannot be 
determined. Other cases from among the earlier experiments, 
where in most instances the size of the transplanted bud was 
small, are inconclusive. On the whole, the cases where the asym- 
metry can be determined with any degree of certainty seem to 
follow the rules. Only a single case thus far examined is clearly 
exceptional. 
" Tr. E. 148 and 154. ^o Tr. E. 120. 
28 Tr. E. 135, 136, 139, and 140. " Tr. E. 127. 
2» Tr. E. 124 and 169. ^^ Tr. E. 107. 
